public static function clear_model_files($modelid) {
        $fs = get_file_storage();
        return $fs->delete_area_files(\context_system::instance()->id, 'analytics', false, $modelid);
    }
public static function clear_model_files($modelid) {
        $fs = get_file_storage();
        return $fs->delete_area_files(\context_system::instance()->id, 'analytics', false, $modelid);
    }
public static function clear_model_files ( $ modelid ) { $ fs = get_file_storage ( ) ; return $ fs -> delete_area_files ( \ context_system :: instance ( ) -> id , 'analytics' , false , $ modelid ) ; }
Delete all files of a model.

@param int $modelid
@return bool
Delete all files of a model .