diff --git a/homeassistant/components/api.py b/homeassistant/components/api.py
index 11f1826549e..0764e84915f 100644
--- a/homeassistant/components/api.py
+++ b/homeassistant/components/api.py
@@ -63,6 +63,9 @@ def setup(hass, config):
     hass.http.register_path(
         'PUT', re.compile(r'/api/states/(?P<entity_id>[a-zA-Z\._0-9]+)'),
         _handle_post_state_entity)
+    hass.http.register_path(
+        'DELETE', re.compile(r'/api/states/(?P<entity_id>[a-zA-Z\._0-9]+)'),
+        _handle_delete_state_entity)
 
     # /events
     hass.http.register_path('GET', URL_API_EVENTS, _handle_get_api_events)
@@ -240,6 +243,22 @@ def _handle_post_state_entity(handler, path_match, data):
         location=URL_API_STATES_ENTITY.format(entity_id))
 
 
+def _handle_delete_state_entity(handler, path_match, data):
+    """Handle request to delete an entity from state machine.
+
+    This handles the following paths:
+    /api/states/<entity_id>
+    """
+    entity_id = path_match.group('entity_id')
+
+    if handler.server.hass.states.remove(entity_id):
+        handler.write_json_message(
+            "Entity not found", HTTP_NOT_FOUND)
+    else:
+        handler.write_json_message(
+            "Entity removed", HTTP_OK)
+
+
 def _handle_get_api_events(handler, path_match, data):
     """ Handles getting overview of event listeners. """
     handler.write_json(_events_json(handler.server.hass))
@@ -258,6 +277,7 @@ def _handle_api_post_events_event(handler, path_match, event_data):
     if event_data is not None and not isinstance(event_data, dict):
         handler.write_json_message(
             "event_data should be an object", HTTP_UNPROCESSABLE_ENTITY)
+        return
 
     event_origin = ha.EventOrigin.remote
 
diff --git a/homeassistant/remote.py b/homeassistant/remote.py
index 3b47b60365c..6b55622adce 100644
--- a/homeassistant/remote.py
+++ b/homeassistant/remote.py
@@ -247,6 +247,13 @@ class StateMachine(ha.StateMachine):
 
         bus.listen(ha.EVENT_STATE_CHANGED, self._state_changed_listener)
 
+    def remove(self, entity_id):
+        """Remove the state of an entity.
+
+        Returns boolean to indicate if an entity was removed.
+        """
+        return remove_state(self._api, entity_id)
+
     def set(self, entity_id, new_state, attributes=None):
         """ Calls set_state on remote API . """
         set_state(self._api, entity_id, new_state, attributes)
@@ -258,7 +265,10 @@ class StateMachine(ha.StateMachine):
 
     def _state_changed_listener(self, event):
         """ Listens for state changed events and applies them. """
-        self._states[event.data['entity_id']] = event.data['new_state']
+        if event.data['new_state'] is None:
+            self._states.pop(event.data['entity_id'], None)
+        else:
+            self._states[event.data['entity_id']] = event.data['new_state']
 
 
 class JSONEncoder(json.JSONEncoder):
@@ -415,6 +425,26 @@ def get_states(api):
         return []
 
 
+def remove_state(api, entity_id):
+    """Call API to remove state for entity_id.
+
+    Returns True if entity is gone (removed/never existed).
+    """
+    try:
+        req = api(METHOD_DELETE, URL_API_STATES_ENTITY.format(entity_id))
+
+        if req.status_code in (200, 404):
+            return True
+
+        _LOGGER.error("Error removing state: %d - %s",
+                      req.status_code, req.text)
+        return False
+    except HomeAssistantError:
+        _LOGGER.exception("Error removing state")
+
+        return False
+
+
 def set_state(api, entity_id, new_state, attributes=None):
     """
     Tells API to update state for entity_id.
diff --git a/tests/test_remote.py b/tests/test_remote.py
index 777f1c30e84..bf6a916f22c 100644
--- a/tests/test_remote.py
+++ b/tests/test_remote.py
@@ -135,9 +135,17 @@ class TestRemoteMethods(unittest.TestCase):
         self.assertEqual(hass.states.all(), remote.get_states(master_api))
         self.assertEqual([], remote.get_states(broken_api))
 
+    def test_remove_state(self):
+        """ Test Python API set_state. """
+        hass.states.set('test.remove_state', 'set_test')
+
+        self.assertIn('test.remove_state', hass.states.entity_ids())
+        remote.remove_state(master_api, 'test.remove_state')
+        self.assertNotIn('test.remove_state', hass.states.entity_ids())
+
     def test_set_state(self):
         """ Test Python API set_state. """
-        hass.states.set('test.test', 'set_test')
+        remote.set_state(master_api, 'test.test', 'set_test')
 
         state = hass.states.get('test.test')
 
@@ -225,6 +233,29 @@ class TestRemoteClasses(unittest.TestCase):
         self.assertEqual("remote.statemachine test",
                          slave.states.get("remote.test").state)
 
+    def test_statemachine_remove_from_master(self):
+        hass.states.set("remote.master_remove", "remove me!")
+        hass.pool.block_till_done()
+
+        self.assertIn('remote.master_remove', slave.states.entity_ids())
+
+        hass.states.remove("remote.master_remove")
+        hass.pool.block_till_done()
+
+        self.assertNotIn('remote.master_remove', slave.states.entity_ids())
+
+    def test_statemachine_remove_from_slave(self):
+        hass.states.set("remote.slave_remove", "remove me!")
+        hass.pool.block_till_done()
+
+        self.assertIn('remote.slave_remove', slave.states.entity_ids())
+
+        self.assertTrue(slave.states.remove("remote.slave_remove"))
+        slave.pool.block_till_done()
+        hass.pool.block_till_done()
+
+        self.assertNotIn('remote.slave_remove', slave.states.entity_ids())
+
     def test_eventbus_fire(self):
         """ Test if events fired from the eventbus get fired. """
         test_value = []