If you are using Google apps to host your domain email, calendar, contacts, etc, then you likely know about this calendar event deletion problem. If you’ve been wondering I, like I have, here’s the answer I found:

iCal events won’t delete with Google sync. They will keep coming back until further notice. Google has set this up intentionally and they offer some insight below. 

This is an intention, but temporary change that was introduced after Apple’s Mac OS X 10.7 and iOS5 launches. The deletion block was put in place to eliminate any risk that a user events could be deleted when syncing between Google Calendar and the Apple products.

There is currently the following information in our ‘Known Issues’ page:

“Events deleted in iCal on Mac OS are not deleted in Google Calendar until further notice.

Setting up iCloud sync caused events to be unexpectedly wiped from Google Calendar for some of our users who were syncing information between iCal and Google Calendar. This unwanted deletion took place between 10/11 and 10/14. We have since restored deleted events and invitees. Please note we’re only able to restore invitees who are Google Calendar users; guests who are non-Google Calendar users (i.e. Outlook users, Yahoo! users) could not be recovered and will need to be re-invited manually.

In response to the above issue, we have stopped deleting events if the delete request comes from iCal. Until further notice, deleting any event in iCal on Mac OS will not remove this event from Google Calendar, but all other requests like creating events or changing existing events will be synced properly.

As a workaround, we suggest you remove events in the web version of Google Calendar (calendar.google.com) – all changes made in the web calendar are properly synced to your iCal.”

This block will be deleted at some point in the near future, with the date being communicated to users nearer the time.

via ICAL EVENTS WON’T DELETE WITH GOOGLE SYNC. EVENTS KEEP COMING BACK. WHY ??? FIX ??? – Calendar Help.