Workgroup::unpin

static function unpin(int $groupId, string $mode = ''): ?bool
{
	if (
		$groupId <= 0
		|| !HelperWorkgroupAccess::canView(['groupId' => $groupId])
		|| !($isPinned = static::getIsPinned($groupId, $mode))
	)
	{
		return false;
	}

	$tableDeleteResult = WorkgroupPinTable::delete($isPinned->get('ID'));
	if (!$tableDeleteResult->isSuccess())
	{
		return null;
	}

	static::sendPinChangedPushEvent($groupId, User::getCurrentUserId(), 'unpin');

	return true;
}