diff --git a/CHANGELOG.md b/CHANGELOG.md
index e1fe424b25..b193c190a3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -237,6 +237,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 
 - Removed deprecated `profiled_functions` argument from `PyTorchProfiler` ([#9178](https://github.com/PyTorchLightning/pytorch-lightning/pull/9178))
 
+
+- Removed deprecated property `Trainer.running_sanity_check` in favor of `Trainer.sanity_checking` ([#9209](https://github.com/PyTorchLightning/pytorch-lightning/pull/9209))
+
 ### Fixed
 
 - Fixed save/load/resume from checkpoint for DeepSpeed Plugin (
diff --git a/pytorch_lightning/trainer/deprecated_api.py b/pytorch_lightning/trainer/deprecated_api.py
index a650c6bfe7..e4f0f410fc 100644
--- a/pytorch_lightning/trainer/deprecated_api.py
+++ b/pytorch_lightning/trainer/deprecated_api.py
@@ -17,16 +17,8 @@ from pytorch_lightning.utilities import rank_zero_deprecation
 
 class DeprecatedTrainerAttributes:
 
-    sanity_checking: bool
     fit_loop: FitLoop
 
-    @property
-    def running_sanity_check(self) -> bool:
-        rank_zero_deprecation(
-            "`Trainer.running_sanity_check` has been renamed to `Trainer.sanity_checking` and will be removed in v1.5."
-        )
-        return self.sanity_checking
-
     @property
     def train_loop(self) -> FitLoop:
         rank_zero_deprecation(
diff --git a/tests/deprecated_api/test_remove_1-5.py b/tests/deprecated_api/test_remove_1-5.py
index e3f4d987ef..735574dda1 100644
--- a/tests/deprecated_api/test_remove_1-5.py
+++ b/tests/deprecated_api/test_remove_1-5.py
@@ -25,12 +25,6 @@ from tests.helpers.runif import RunIf
 from tests.helpers.utils import no_warning_call
 
 
-def test_v1_5_0_running_sanity_check():
-    trainer = Trainer()
-    with pytest.deprecated_call(match="has been renamed to `Trainer.sanity_checking`"):
-        assert not trainer.running_sanity_check
-
-
 def test_v1_5_0_model_checkpoint_period(tmpdir):
     with no_warning_call(DeprecationWarning):
         ModelCheckpoint(dirpath=tmpdir)