$cityCookie = Yii::$app->request->cookies[self::COOKIE_CITY_ID];
$cityCookie->expire = -1;
$cityCookie->path = '/';
$cityCookie->value = null;

setcookie(self::COOKIE_CITY_ID, null, -1, '/');

$cookies = Yii::$app->response->cookies;
// add a new cookie to the response to be sent
$cookies->add(new yiiwebCookie([
    'name' => 'language',
    'value' => 'zh-CN',
]));
// remove a cookie
$cookies->remove('language');