If the auction hasn't ended just go in and cancel your bid, that way I don't have to relist it and the person that was the bidder just under you will take it
I have never done it, but I have had customers who have go to bottom of auction page where its about Listia etc. and go under help and type in how to cancel bid
at the bottom of the auction pages is a list of things about Listia, I think if you click on some of them you will find it or go under Listia help and inquire