When you delete an Event, the corresponding ExtCal entry remains.

Add this code to "admin.mls_events.php::removeMLS_events"

global $cnf_mls_events;

//ExtCal 2 integration
if($cnf_mls_events["extcal_integration"]) {
//Integration is enabled...
$database->setQuery( "SELECT `extcal_id` FROM `#__mls_events` WHERE `id` IN ($cids)" );
$events = $database->loadObjectList();
foreach($events as $event) {
$extids .= (!$extids)?$event->extcal_id:','.$event->extcal_id;
}
$database->setQuery( "DELETE FROM `#__extcal_events` WHERE `extid` IN ($extids)" );
if (!$database->query()) {
echo " alert('".$database->getErrorMsg()."'); window.history.go(-1); \n";
}
}
?>