public static function deleteUser($id)
    {
        $activity = static::find()->where(['user_id' => $id])->limit(1)->one();
        if (empty($activity) || !$activity->delete()) {
            Log::error('Cannot delete user activity', $id, __METHOD__);
            return;
        }
        Podium::getInstance()->podiumCache->delete('forum.lastactive');
    }