Removing Trigger Events

Is there a JASS function to remove the last event added to a trigger?

I don't know if you can remove the last added event but you can reset the trigger to it's original form. (all added actions, events and conditions will be removed)

last time I checked Reset didn't help to do this.

The only way was to destroy the trigger

Can you destroy the trigger and then re-add it?

i dont really understand your question. but if you wonder if you can create a trigger by triggers (^^) then yes. of course. though you DO want to clean it fully ;)
i know that the trigger itself, and the TriggerAction leaks, probably TriggerCondition aswell since there exists a native to destroy it. have no idea about the event though.