diff --git a/moto/iot/models.py b/moto/iot/models.py
index 287c71d8c..65fcccf95 100644
--- a/moto/iot/models.py
+++ b/moto/iot/models.py
@@ -695,7 +695,6 @@ class IoTBackend(BaseBackend):
         # can raise ResourceNotFoundError
         thing = self.describe_thing(thing_name)
 
-        # detach all principals
         for k in list(self.principal_things.keys()):
             if k[1] == thing_name:
                 raise ThingStillAttached(thing_name)