Contact the seller and ask them to cancel your bid. The seller is not obligated to agree to your request to cancel the bid.
Per Ebay:
When you bid on or buy an item, you're agreeing to the rules we've put in place for our community. A bid is a binding contract that's active until an auction-style listing ends. Once you place a bid, you need to pay for the item if you're the winning bidder.
lady_madonna
Mentor3 years ago@pineco
Only sellers can cancel bids.
Contact the seller and ask them to cancel your bid. The seller is not obligated to agree to your request to cancel the bid.
Per Ebay:
When you bid on or buy an item, you're agreeing to the rules we've put in place for our community. A bid is a binding contract that's active until an auction-style listing ends. Once you place a bid, you need to pay for the item if you're the winning bidder.
https://www.ebay.com/help/policies/rules-policies-buyers/rules-policies-buyers?id=4206