CAllCrmActivity::OnCalendarEventDelete

static function OnCalendarEventDelete($eventID, $arEventFields)
{
	if(self::$IGNORE_CALENDAR_EVENTS)
	{
		return;
	}

	$dbEntities = self::GetList(
		[],
		['=CALENDAR_EVENT_ID' => $eventID]
	);
	while($arEntity = $dbEntities->Fetch())
	{
		if ($arEntity['PROVIDER_ID'] === "CRM_CALENDAR_SHARING")
		{
			continue;
		}

		self::Delete($arEntity['ID'], false, true, array('SKIP_CALENDAR_EVENT' => true));
	}
}