delete faviourite of currently logged in user

function my_function($deleted_activities) {
       if(empty($deleted_activities))
              return;
foreach((array)$deleted_activities as $item_id)
            bp_activity_remove_user_favorite($item_id);//you may want to pass the user id as second parameter
        }
add_action( 'bp_activity_deleted_activities', 'my_function' );