private function delete($obj)
 {
     $sync = Config::get('database.connections.firebase.sync');
     // `sync` by Default (config)?
     $path = strtolower(get_class($obj)) . 's';
     // plural collection name
     $id = \Firebase::getId($obj);
     // object ID (extracted)
     // Delete if Allowed
     if ($sync !== false || !empty($obj->firebase)) {
         \Firebase::delete('/' . $path . '/' . $id);
     }
 }