No, according to our terms bids are binding.
Removing a bid can suddenly make another bidder into the leading bidder. That bidder might have given up and bought a similar object elsewhere instead.
It might also cause suspicions of fake bids.
It also wouldn't be fair to the seller who counts on the item being sold once it receives a winning bid.
Note that you can lower your max bid if you are the leading bidder and your max bid exceeds the placed bid.