diff --git a/mozharness/builds/thunderbird_source.py b/mozharness/builds/thunderbird_source.py
deleted file mode 100644
index b55344341d..0000000000
--- a/mozharness/builds/thunderbird_source.py
+++ /dev/null
@@ -1,13 +0,0 @@
-config = {
-    'default_actions': ['package-source'],
-    'objdir': 'obj-firefox',
-    'stage_platform': 'source',  # Not used, but required by the script
-    'buildbot_json_path': 'buildprops.json',
-    'app_ini_path': 'FAKE',  # Not used, but required by the script
-    'env': {
-        'HG_SHARE_BASE_DIR': '/builds/hg-shared',
-        'TINDERBOX_OUTPUT': '1',
-        'LC_ALL': 'C',
-    },
-    'src_mozconfig': 'comm/mail/config/mozconfigs/linux64/source',
-}
diff --git a/taskcluster/ci/beetmover-source/kind.yml b/taskcluster/ci/beetmover-source/kind.yml
deleted file mode 100644
index aedd746d0e..0000000000
--- a/taskcluster/ci/beetmover-source/kind.yml
+++ /dev/null
@@ -1,18 +0,0 @@
-# This Source Code Form is subject to the terms of the Mozilla Public
-# License, v. 2.0. If a copy of the MPL was not distributed with this
-# file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
-loader: taskgraph.loader.single_dep:loader
-
-transforms:
-    - taskgraph.transforms.name_sanity:transforms
-    - taskgraph.transforms.beetmover:transforms
-    - taskgraph.transforms.beetmover_source:transforms
-    - taskgraph.transforms.release_notifications:transforms
-    - taskgraph.transforms.task:transforms
-
-kind-dependencies:
-    - release-source-signing
-
-job-template:
-    shipping-phase: promote
diff --git a/taskcluster/ci/release-source-signing/kind.yml b/taskcluster/ci/release-source-signing/kind.yml
deleted file mode 100644
index bedd8d3291..0000000000
--- a/taskcluster/ci/release-source-signing/kind.yml
+++ /dev/null
@@ -1,18 +0,0 @@
-# This Source Code Form is subject to the terms of the Mozilla Public
-# License, v. 2.0. If a copy of the MPL was not distributed with this
-# file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
-loader: taskgraph.loader.single_dep:loader
-
-transforms:
-    - taskgraph.transforms.name_sanity:transforms
-    - taskgraph.transforms.build_signing:transforms
-    - taskgraph.transforms.signing:transforms
-    - taskgraph.transforms.release_notifications:transforms
-    - taskgraph.transforms.task:transforms
-
-kind-dependencies:
-    - release-source
-
-job-template:
-    shipping-phase: promote
diff --git a/taskcluster/ci/release-source/kind.yml b/taskcluster/ci/release-source/kind.yml
deleted file mode 100644
index 7bc9193c57..0000000000
--- a/taskcluster/ci/release-source/kind.yml
+++ /dev/null
@@ -1,48 +0,0 @@
-# This Source Code Form is subject to the terms of the Mozilla Public
-# License, v. 2.0. If a copy of the MPL was not distributed with this
-# file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
-loader: taskgraph.loader.transform:loader
-
-kind-dependencies:
-    - toolchain
-
-transforms:
-    - taskgraph.transforms.build:transforms
-    - taskgraph.transforms.build_attrs:transforms
-    - taskgraph.transforms.build_lints:transforms
-    - taskgraph.transforms.use_toolchains:transforms
-    - taskgraph.transforms.release_notifications:transforms
-    - taskgraph.transforms.job:transforms
-    - taskgraph.transforms.task:transforms
-
-job-defaults:
-    shipping-phase: promote
-    treeherder:
-        symbol: Src
-    worker-type: aws-provisioner-v1/gecko-{level}-b-linux
-    worker:
-        max-run-time: 3600
-        env:
-            PKG_SRCPACK_BASENAME: source
-    run:
-        using: mozharness
-        comm-checkout: true
-        actions: [package-source]
-        script: "mozharness/scripts/fx_desktop_build.py"
-        config-paths:
-            - comm/mozharness
-        config:
-            - builds/thunderbird_source.py
-        options: []
-        tooltool-downloads: public
-        need-xvfb: false
-    run-on-projects: []
-    optimization: {}
-
-jobs:
-    thunderbird-source/opt:
-        description: "Thunderbird source builder"
-        treeherder:
-            platform: thunderbird-release/opt
-        shipping-product: thunderbird