--- a/mozilla-tests/thunderbird_config.py
+++ b/mozilla-tests/thunderbird_config.py
@@ -46,20 +46,19 @@ PLATFORMS = {
     'macosx64': {},
     'win32': {},
     'linux': {},
     'linux64': {},
 }
 
 builder_prefix = "TB "
 
-PLATFORMS['macosx64']['slave_platforms'] = ['snowleopard', 'yosemite', 'yosemite_r7']
+PLATFORMS['macosx64']['slave_platforms'] = ['snowleopard', 'yosemite_r7']
 PLATFORMS['macosx64']['env_name'] = 'mac-perf'
 PLATFORMS['macosx64']['snowleopard'] = {'name': builder_prefix + "Rev4 MacOSX Snow Leopard 10.6"}
-PLATFORMS['macosx64']['yosemite'] = {'name': builder_prefix + "Rev5 MacOSX Yosemite 10.10"}
 PLATFORMS['macosx64']['yosemite_r7'] = {'name': builder_prefix + "Rev7 MacOSX Yosemite 10.10.5"}
 PLATFORMS['macosx64']['stage_product'] = 'thunderbird'
 PLATFORMS['macosx64']['mozharness_config'] = {
     'mozharness_python': '/tools/buildbot/bin/python',
     'hg_bin': 'hg',
     'reboot_command': ['/tools/buildbot/bin/python'] + MOZHARNESS_REBOOT_CMD,
     'system_bits': '64',
 }
@@ -266,28 +265,16 @@ PLATFORM_UNITTEST_VARS = {
                 'xpcshell': {
                     'config_files': ["unittests/mac_unittest.py"],
                 },
                 'mozmill': {
                     'config_files': ["unittests/mac_unittest.py"],
                 },
             },
         },
-        'yosemite': {
-            'opt_unittest_suites': UNITTEST_SUITES['opt_unittest_suites'][:],
-            'debug_unittest_suites': UNITTEST_SUITES['debug_unittest_suites'][:],
-            'suite_config': {
-                'xpcshell': {
-                    'config_files': ["unittests/mac_unittest.py"],
-                },
-                'mozmill': {
-                    'config_files': ["unittests/mac_unittest.py"],
-                },
-            },
-        },
         'yosemite_r7': {
             'opt_unittest_suites': UNITTEST_SUITES['opt_unittest_suites'][:],
             'debug_unittest_suites': UNITTEST_SUITES['debug_unittest_suites'][:],
             'suite_config': {
                 'xpcshell': {
                     'config_files': ["unittests/mac_unittest.py"],
                 },
                 'mozmill': {
@@ -469,28 +456,16 @@ for platform in PLATFORMS.keys():
                     try:
                         branch['platforms'][platform][slave_platform][suite_type].remove(mozmill)
                         if MOZMILL_OLD not in branch['platforms'][platform][slave_platform][suite_type]:
                             branch['platforms'][platform][slave_platform][suite_type].append(MOZMILL_OLD)
                     except ValueError:
                         # wasn't in the list anyways
                         pass
 
-# Bug 1230763 - enable r7 on trunk and disable r5 on non-trunk
-ride_trains_branches = []
-for name, branch in items_at_least(BRANCHES, 'gecko_version', 46):
-    ride_trains_branches.append(name)
-
-not_ride_trains_branches = []
-for name, branch in items_before(BRANCHES, 'gecko_version', 46):
-    not_ride_trains_branches.append(name)
-
-delete_slave_platform(BRANCHES, PLATFORMS, {'macosx64': 'yosemite_r7'}, branch_exclusions=ride_trains_branches)
-delete_slave_platform(BRANCHES, PLATFORMS, {'macosx64': 'yosemite'}, branch_exclusions=not_ride_trains_branches)
-
 # Enable mozharness pinning
 for _, branch in items_at_least(BRANCHES, 'gecko_version', 30):
     branch['script_repo_manifest'] = \
         "https://hg.mozilla.org/%(moz_repo_path)s/raw-file/default/" + \
         "testing/mozharness/mozharness.json"
     # mozharness_archiver_repo_path tells the factory to use a copy of mozharness from within the
     #  gecko tree and also allows us to overwrite which gecko repo to use. Useful for platforms
     # like Thunderbird