public function unimpersonateUser()
    {
        $realId = $this->session->remove('__realId');
        if ($realId !== null) {
            $this->user->identity->remove();
            $this->session->set($this->user->idParam, $realId);
            $identity = User::findOne($realId);
            $this->user->setIdentity($identity);
            $this->restoreBackedUpToken();
        }
    }