diff --git a/testing/mozharness/configs/unittests/thunderbird_buildbot.py b/testing/mozharness/configs/unittests/thunderbird_buildbot.py
deleted file mode 100644
index f928dc6e9197..000000000000
--- a/testing/mozharness/configs/unittests/thunderbird_buildbot.py
+++ /dev/null
@@ -1,20 +0,0 @@
-import platform
-
-# Specify tooltool directory for thunderbird buildbot tests explicitly.
-# The default configuration in `linux_unittest.py` specifies a
-# taskcluster-specific location. Override that here until thunderbird is being
-# built on taskcluster.
-# See https://bugzilla.mozilla.org/show_bug.cgi?id=1356520
-# and https://bugzilla.mozilla.org/show_bug.cgi?id=1371734
-config = {
-    "tooltool_cache": "/builds/tooltool_cache",
-}
-
-# Specify virtualenv directory for thunderbird buildbot tests explicitly.
-# The default configuration in `linux_unittest.py` specifies a path that
-# doesn't exist on buildbot. We need to specify the other paths here too, since
-# config entries are overriden wholesale.
-if platform.system() == "Linux":
-    config["exes"] = {
-        "python": "/tools/buildbot/bin/python",
-    }
diff --git a/testing/mozharness/configs/unittests/thunderbird_extra.py b/testing/mozharness/configs/unittests/thunderbird_extra.py
deleted file mode 100644
index 2021b9d55237..000000000000
--- a/testing/mozharness/configs/unittests/thunderbird_extra.py
+++ /dev/null
@@ -1,17 +0,0 @@
-#####
-config = {
-    "application": "thunderbird",
-    "minimum_tests_zip_dirs": [
-        "bin/*",
-        "certs/*",
-        "config/*",
-        "extensions/*",
-        "marionette/*",
-        "modules/*",
-        "mozbase/*",
-        "tools/*",
-    ],
-    "all_mozmill_suites": {
-        "mozmill": ["--list=tests/mozmill/mozmilltests.list"],
-    },
-}