diff --git a/src/core/entity.py b/src/core/entity.py
index 469da09..3565917 100644
--- a/src/core/entity.py
+++ b/src/core/entity.py
@@ -22,7 +22,6 @@ class Entity:
         self._room = room
         self._device_type = device_type.strip().lower()
         self._groups = set(groups)
-        self.__is_on__: bool | None = None
 
     @property
     def id(self) -> str:
@@ -52,20 +51,13 @@ class Entity:
         """Implements an entity specific update operation to get the latest state."""
         raise EntityOpNotSupportedError("update")
 
-    async def toggle_state(self):
-        """Turns entity on, if off, and vice versa, if supported."""
-        if self.__is_on__ == False:  # Neither True nor None
-            await self.turn_on()
-        else:
-            await self.turn_off()
-
     async def turn_on(self):
         """Turns entity on, if action supported."""
-        self.__is_on__ = True  # TODO: What if action unsuccessful?
+        raise EntityOpNotSupportedError("turn_on")
 
     async def turn_off(self):
         """Turns entity on, if action supported."""
-        self.__is_on__ = False  # TODO: What if action unsuccessful?
+        raise EntityOpNotSupportedError("turn_off")
 
     async def set_brightness(self, brightness: float):
         """Does not turn an entity on if brightness > 0 and entity turned off."""