Under the My Account -> Members -> Buying -> Current Bids area, you can see all items that you have bid upon.
You will notice that there is an option to retract a bid. If you select this option, it will remove your current bid plus all previous bids that you had placed upon that item and only that one item UNLESS the auction of the item has 12 or less hours until it ends. If that is the case then NO bid retraction is allowed.
Of course we don't wish you to retract bids and encourage you to contact the Auctioneer if there are questions or problems that would make you want to retract bids. Sometimes if it's something as simple as the pickup date/time needs to be different or if a family emergency has occurred, the Auctioneer will possibly work with you if notified of these events.