I was having to do some weekend work, so on my iPod Touch I set up an event on the built-in Calendar app for 7am on Saturdays. I made this to repeat for every weekend and created an alert (alarm) to remind me. It worked fine.
When that job ended, I went to the event and wiped it out (so, no repeats, either)
Somehow, though, the alert is still there - the alarm wakes me at 7am on Saturdays, even though there is nothing on the Calendar any more - no events show. I've checked the Clock app as well, and there are no alarms set.