diff --git a/.cron.yml b/.cron.yml
index 8d6284a2ba59..45bb76832df0 100644
--- a/.cron.yml
+++ b/.cron.yml
@@ -119,7 +119,6 @@ jobs:
       run-on-projects:
           - mozilla-beta
           - mozilla-release
-          - mozilla-esr91
           - mozilla-esr102
           - elm
       # For all non m-c jobs we just run once daily matching the 10 UTC
@@ -193,7 +192,6 @@ jobs:
           - mozilla-central
           - mozilla-beta
           - mozilla-release
-          - mozilla-esr91
           - mozilla-esr102
       when:
           by-project:
@@ -207,9 +205,6 @@ jobs:
               mozilla-release:
                   - {hour: 7, minute: 0}
                   - {hour: 19, minute: 0}
-              mozilla-esr91:
-                  - {hour: 7, minute: 0}
-                  - {hour: 19, minute: 0}
               mozilla-esr102:
                   - {hour: 7, minute: 0}
                   - {hour: 19, minute: 0}
@@ -223,7 +218,6 @@ jobs:
           - mozilla-central
           - mozilla-beta
           - mozilla-release
-          - mozilla-esr91
           - mozilla-esr102
       when:
           - {weekday: 'Monday', hour: 8, minute: 0}
diff --git a/python/mozbuild/mozbuild/artifacts.py b/python/mozbuild/mozbuild/artifacts.py
index 2db4c907cf9d..610c36440071 100644
--- a/python/mozbuild/mozbuild/artifacts.py
+++ b/python/mozbuild/mozbuild/artifacts.py
@@ -103,7 +103,6 @@ class ArtifactJob(object):
     ]
     # The list below list should be updated when we have new ESRs.
     esr_candidate_trees = [
-        "releases/mozilla-esr91",
         "releases/mozilla-esr102",
     ]
     try_tree = "try"
@@ -773,7 +772,6 @@ class ThunderbirdMixin(object):
     ]
     # The list below list should be updated when we have new ESRs.
     esr_candidate_trees = [
-        "releases/comm-esr91",
         "releases/comm-esr102",
     ]
 
diff --git a/taskcluster/ci/build/linux.yml b/taskcluster/ci/build/linux.yml
index 142a8bcc8dff..39a054e43e17 100644
--- a/taskcluster/ci/build/linux.yml
+++ b/taskcluster/ci/build/linux.yml
@@ -565,7 +565,7 @@ linux/opt:
         secrets: true
         tooltool-downloads: public
         need-xvfb: true
-    run-on-projects: ['mozilla-beta', 'mozilla-release', 'mozilla-esr91', 'mozilla-esr102']
+    run-on-projects: ['mozilla-beta', 'mozilla-release', 'mozilla-esr102']
     use-sccache: true
     fetches:
         toolchain:
diff --git a/taskcluster/ci/build/windows-mingw.yml b/taskcluster/ci/build/windows-mingw.yml
index d9f7cb65c4ef..fd4f2e105926 100644
--- a/taskcluster/ci/build/windows-mingw.yml
+++ b/taskcluster/ci/build/windows-mingw.yml
@@ -34,7 +34,7 @@ win32-mingwclang/opt:
             - builds/releng_base_windows_32_mingw_builds.py
             - builds/releng_sub_windows_configs/32_mingwclang.py
         mozconfig-variant: mingwclang
-    run-on-projects: ['mozilla-central', 'mozilla-esr91', 'mozilla-esr102']
+    run-on-projects: ['mozilla-central', 'mozilla-esr102']
     use-sccache: true
     fetches:
         toolchain:
@@ -71,7 +71,7 @@ win32-mingwclang/debug:
             - builds/releng_base_windows_32_mingw_builds.py
             - builds/releng_sub_windows_configs/32_mingwclang.py
         mozconfig-variant: mingwclang-debug
-    run-on-projects: ['mozilla-central', 'mozilla-esr91', 'mozilla-esr102']
+    run-on-projects: ['mozilla-central', 'mozilla-esr102']
     use-sccache: true
     fetches:
         toolchain:
@@ -108,7 +108,7 @@ win64-mingwclang/opt:
             - builds/releng_base_windows_64_mingw_builds.py
             - builds/releng_sub_windows_configs/64_mingwclang.py
         mozconfig-variant: mingwclang
-    run-on-projects: ['mozilla-central', 'mozilla-esr91', 'mozilla-esr102']
+    run-on-projects: ['mozilla-central', 'mozilla-esr102']
     use-sccache: true
     fetches:
         toolchain:
@@ -145,7 +145,7 @@ win64-mingwclang/debug:
             - builds/releng_base_windows_64_mingw_builds.py
             - builds/releng_sub_windows_configs/64_mingwclang.py
         mozconfig-variant: mingwclang-debug
-    run-on-projects: ['mozilla-central', 'mozilla-esr91', 'mozilla-esr102']
+    run-on-projects: ['mozilla-central', 'mozilla-esr102']
     use-sccache: true
     fetches:
         toolchain:
diff --git a/taskcluster/ci/config.yml b/taskcluster/ci/config.yml
index c47039585e24..33a2709373c5 100644
--- a/taskcluster/ci/config.yml
+++ b/taskcluster/ci/config.yml
@@ -389,19 +389,6 @@ merge-automation:
             end-tag: 'FIREFOX_NIGHTLY_{major_version}_END'
             to-repo: 'https://hg.mozilla.org/mozilla-central'
             to-branch: 'central'
-        bump-esr91:
-            fetch-version-from: "browser/config/version.txt"
-            version-files:
-                - filename: "config/milestone.txt"
-                  version-bump: "minor"
-                - filename: "browser/config/version.txt"
-                  version-bump: "minor"
-                - filename: "browser/config/version_display.txt"
-                  version-bump: "minor"
-            replacements: []
-            merge-old-head: false
-            to-repo: 'https://hg.mozilla.org/releases/mozilla-esr91'
-            to-branch: 'esr91'
         bump-esr102:
             fetch-version-from: "browser/config/version.txt"
             version-files:
diff --git a/taskcluster/ci/release-balrog-scheduling/kind.yml b/taskcluster/ci/release-balrog-scheduling/kind.yml
index e59711fdd3b1..0ca6bfc12e00 100644
--- a/taskcluster/ci/release-balrog-scheduling/kind.yml
+++ b/taskcluster/ci/release-balrog-scheduling/kind.yml
@@ -34,14 +34,12 @@ jobs:
                         by-release-type:
                             beta: [32]
                             release: [145]
-                            esr91: [17638]
                             esr102: [17770]
                             default: []
                     staging:
                         by-release-type:
                             beta: [32]
                             release: [145]
-                            esr91: [889]
                             esr102: [902]
                             default: []
             background-rate:
diff --git a/taskcluster/ci/release-balrog-submit-toplevel/kind.yml b/taskcluster/ci/release-balrog-submit-toplevel/kind.yml
index b0158f501d33..555b75176c5c 100644
--- a/taskcluster/ci/release-balrog-submit-toplevel/kind.yml
+++ b/taskcluster/ci/release-balrog-submit-toplevel/kind.yml
@@ -46,7 +46,6 @@ jobs:
                 by-release-type:
                     beta: ["firefox-beta-cdntest", "firefox-beta-localtest"]
                     release(-rc)?: ["firefox-release-cdntest", "firefox-release-localtest"]
-                    esr91: ["firefox-esr91-cdntest", "firefox-esr91-localtest"]
                     esr102: ["firefox-esr102-cdntest", "firefox-esr102-localtest"]
                     default: []
             pin-channels:
diff --git a/taskcluster/ci/release-bouncer-sub/kind.yml b/taskcluster/ci/release-bouncer-sub/kind.yml
index 614fad048214..f1598ebb31bb 100644
--- a/taskcluster/ci/release-bouncer-sub/kind.yml
+++ b/taskcluster/ci/release-bouncer-sub/kind.yml
@@ -43,7 +43,6 @@ jobs:
         bouncer-products:
             by-release-type:
                 default: ['complete-mar', 'installer', 'installer-ssl', 'partial-mar', 'stub-installer', 'msi', 'msix', 'pkg']
-                esr91: ['complete-mar', 'installer', 'installer-ssl', 'partial-mar', 'msi', 'pkg']
                 esr102: ['complete-mar', 'installer', 'installer-ssl', 'partial-mar', 'msi', 'msix', 'pkg']
         shipping-product: firefox
         treeherder:
diff --git a/taskcluster/ci/release-update-verify-config/kind.yml b/taskcluster/ci/release-update-verify-config/kind.yml
index e3236bd60a4f..2cc55b0bf091 100644
--- a/taskcluster/ci/release-update-verify-config/kind.yml
+++ b/taskcluster/ci/release-update-verify-config/kind.yml
@@ -53,7 +53,6 @@ job-defaults:
             by-release-type:
                 beta: "72.0"
                 release(-rc)?: "72.0.2"
-                esr91: "68.0esr"
                 esr102: "68.0esr"
                 default: "default"
 
diff --git a/taskcluster/docs/attributes.rst b/taskcluster/docs/attributes.rst
index 304dc9ec4c91..dc930e5a8e60 100644
--- a/taskcluster/docs/attributes.rst
+++ b/taskcluster/docs/attributes.rst
@@ -45,7 +45,6 @@ Project names are the repositories.  They can be:
 * `mozilla-central`
 * `mozilla-beta`
 * `mozilla-release`
-* `mozilla-esr91`
 * `mozilla-esr102`
 * ... A partial list can be found in taskcluster/gecko_taskgraph/util/attributes.py
 
diff --git a/taskcluster/docs/parameters.rst b/taskcluster/docs/parameters.rst
index d0b0f958d0bf..b2bc2c3bfb1b 100644
--- a/taskcluster/docs/parameters.rst
+++ b/taskcluster/docs/parameters.rst
@@ -179,7 +179,7 @@ Release Promotion
    Specify the next version for version bump tasks.
 
 ``release_type``
-   The type of release being promoted. One of "nightly", "beta", "esr91", "esr102", "release-rc", or "release".
+   The type of release being promoted. One of "nightly", "beta", "esr102", "release-rc", or "release".
 
 ``release_eta``
    The time and date when a release is scheduled to live. This value is passed to Balrog.
diff --git a/taskcluster/gecko_taskgraph/decision.py b/taskcluster/gecko_taskgraph/decision.py
index cb6eb56abdf2..276732cb78a8 100644
--- a/taskcluster/gecko_taskgraph/decision.py
+++ b/taskcluster/gecko_taskgraph/decision.py
@@ -79,10 +79,6 @@ PER_PROJECT_PARAMETERS = {
         "target_tasks_method": "mozilla_release_tasks",
         "release_type": "release",
     },
-    "mozilla-esr91": {
-        "target_tasks_method": "mozilla_esr91_tasks",
-        "release_type": "esr91",
-    },
     "mozilla-esr102": {
         "target_tasks_method": "mozilla_esr102_tasks",
         "release_type": "esr102",
diff --git a/taskcluster/gecko_taskgraph/target_tasks.py b/taskcluster/gecko_taskgraph/target_tasks.py
index add8cd6b6934..1da1a9df91db 100644
--- a/taskcluster/gecko_taskgraph/target_tasks.py
+++ b/taskcluster/gecko_taskgraph/target_tasks.py
@@ -532,30 +532,6 @@ def target_tasks_mozilla_release(full_task_graph, parameters, graph_config):
     ]
 
 
-@_target_task("mozilla_esr91_tasks")
-def target_tasks_mozilla_esr91(full_task_graph, parameters, graph_config):
-    """Select the set of tasks required for a promotable beta or release build
-    of desktop, without android CI. The candidates build process involves a pipeline
-    of builds and signing, but does not include beetmover or balrog jobs."""
-
-    def filter(task):
-        if not filter_release_tasks(task, parameters):
-            return False
-
-        if not standard_filter(task, parameters):
-            return False
-
-        platform = task.attributes.get("build_platform")
-
-        # Android is not built on esr91.
-        if platform and "android" in platform:
-            return False
-
-        return True
-
-    return [l for l, t in full_task_graph.tasks.items() if filter(t)]
-
-
 @_target_task("mozilla_esr102_tasks")
 def target_tasks_mozilla_esr102(full_task_graph, parameters, graph_config):
     """Select the set of tasks required for a promotable beta or release build
@@ -1101,7 +1077,6 @@ def target_tasks_release_simulation(full_task_graph, parameters, graph_config):
         "nightly": "mozilla-central",
         "beta": "mozilla-beta",
         "release": "mozilla-release",
-        "esr91": "mozilla-esr91",
         "esr102": "mozilla-esr102",
     }
     target_project = project_by_release.get(parameters["release_type"])
diff --git a/taskcluster/gecko_taskgraph/util/attributes.py b/taskcluster/gecko_taskgraph/util/attributes.py
index 1eac7d760ad6..bdb3328f3527 100644
--- a/taskcluster/gecko_taskgraph/util/attributes.py
+++ b/taskcluster/gecko_taskgraph/util/attributes.py
@@ -16,11 +16,9 @@ RELEASE_PROJECTS = {
     "mozilla-central",
     "mozilla-beta",
     "mozilla-release",
-    "mozilla-esr91",
     "mozilla-esr102",
     "comm-central",
     "comm-beta",
-    "comm-esr91",
     "comm-esr102",
     "oak",
 }
diff --git a/taskcluster/gecko_taskgraph/util/scriptworker.py b/taskcluster/gecko_taskgraph/util/scriptworker.py
index 3e15056c9a08..22578667a655 100644
--- a/taskcluster/gecko_taskgraph/util/scriptworker.py
+++ b/taskcluster/gecko_taskgraph/util/scriptworker.py
@@ -59,10 +59,8 @@ SIGNING_SCOPE_ALIAS_TO_PROJECT = [
         {
             "mozilla-beta",
             "mozilla-release",
-            "mozilla-esr91",
             "mozilla-esr102",
             "comm-beta",
-            "comm-esr91",
             "comm-esr102",
         },
     ],
@@ -106,10 +104,8 @@ BEETMOVER_SCOPE_ALIAS_TO_PROJECT = [
         {
             "mozilla-beta",
             "mozilla-release",
-            "mozilla-esr91",
             "mozilla-esr102",
             "comm-beta",
-            "comm-esr91",
             "comm-esr102",
         },
     ],
@@ -165,16 +161,9 @@ BALROG_SCOPE_ALIAS_TO_PROJECT = [
         "release",
         {
             "mozilla-release",
-            "comm-esr91",
             "comm-esr102",
         },
     ],
-    [
-        "esr91",
-        {
-            "mozilla-esr91",
-        },
-    ],
     [
         "esr102",
         {
@@ -190,7 +179,6 @@ BALROG_SERVER_SCOPES = {
     "aurora": "balrog:server:aurora",
     "beta": "balrog:server:beta",
     "release": "balrog:server:release",
-    "esr91": "balrog:server:esr",
     "esr102": "balrog:server:esr",
     "default": "balrog:server:dep",
 }
diff --git a/testing/web-platform/manifestdownload.py b/testing/web-platform/manifestdownload.py
index 28ade0ef7e71..c05b361ef9b2 100644
--- a/testing/web-platform/manifestdownload.py
+++ b/testing/web-platform/manifestdownload.py
@@ -92,7 +92,6 @@ def taskcluster_url(logger, commits):
     repos = {
         "mozilla-central": "mozilla-central",
         "integration/autoland": "autoland",
-        "releases/mozilla-esr91": "mozilla-esr91",
         "releases/mozilla-esr102": "mozilla-esr102",
     }
     cset_url = (