I have been on my iPad for a couple hours trying to figure this out - so frustrating. Many gave advice on how to get the 'delete' or 'edit' tab, nothing worked. I then went to my yahoo calendar on my lap top and was able to delete it there, and because it's all sync'd together, it deleted it off of all my apple calendars as well! And they say apples are so easy and intuitive.
Tap on the event, then click on "edit". You'll see options for repeating.