EventManager::removeEventHandler

public function removeEventHandler($entity, $eventType, $iEventHandlerKey)
{
	$entity = static::obtainEntity($entity);
	$eventType = static::obtainEventType($entity, $eventType);

	// unsubscribe
	return \Bitrix\Main\EventManager::getInstance()
		->removeEventHandler($entity->getModule(), $eventType, $iEventHandlerKey);
}