I don't have my Evo yet, but since no one else has replied I thought I'd chime in. Have you tried long-pressing the event in your calendar and see if there's a delete option in the menu? Have you tried clicking the event to bring up its details page and then hitting the menu button at the bottom and see if there's a delete option there?
Yes I tried The long press lets you view event or forward , then once you view event you have menu options to send a greeting, add reminder , print or forward. No delete.. which is strange
It allows you to edit the reminder notification but nothing else. ... On the day view there is a delete but when you select it it says select events to delete and nothing comes up I think because it is not considering the birthday an event.
I thought I did the calendar but I had to do it under contact's details. I did go back and try entering directly on the calendar and when I went to delete events my entry did show for it to be deleted. So I think that has to mean I put it under contact details and just didnt remember it, its been wrong for a while so very possible.