Delete an event

To manually delete an event, select it, then press the Delete key on your keyboard. To delete multiple events at once, Shift-select two or more events, then press Delete. Or from the Edit menu, choose Delete.

To automatically delete events that have passed

1.	From the iCal menu, choose "Preferences…," then click the "Advanced" button (shown below).
2.	Check "Delete events" (circled below). An alert dialog opens to warn you that setting this option will automatically delete events older than 60 days (or whatever number of days you decide to use), and asks if you're sure you want to do this. Click "Yes" to delete old events.
3.	Type a number in the text field to set how many days will pass after events before iCal automatically deletes them.