I don't think so. I know there's an option that's Quest - Destroy Quest, but I'm not really sure what it does as I've never used it. I think it's for a timed quest or something, you put Wait x Seconds after the Make Quest action, then put in Destroy Quest. But I'm really not sure, sorry.
I know you can disable them, but if you found the Create Quest thing then you probably know that. What are you trying to do?
Well I'm pretty sure you can edit some of the quests. I'm not sure about if you can delete them or not, though.
Go into the Trigger Editor, and at the top of those drop lists there's an option to search. Use that and type QUEST in, and there's a few options about making and editing and deleting them. I don't really use those much, so I can't help too much.
Ghan has said he has fixed this. Monovertex please confirm this fix. This was only a problem with people that had signatures in the upper levels like not the special members but the respected members.