Yes you can, but there are only (3) three valid reasons to retract a bid, according to eBay rules and regulations.

1) You have entered an incorrect amount because you misplaced a decimal point. Bidding $798 instead of $7.98 - in this instance you may retract your bid, but must immediately rebid the correct amount. You should also enter the reason for your retraction - stating, "typographical error, misplaced decimal point". If you do not place another bid, the retraction will be in violation of eBay's policy and could result in your suspension.

2) The description in the auction listing was significantly changed, after your bid was placed. There are time stamps for listing revisions as well as the bidding history to monitor these facts.

3) You are unable to contact your seller by e-mail or phone, due to incorrect contact information. Example: Phone number not in service, or you tried emailing a message to the seller and it comes back undeliverable (bounced).