As a seller, you can cancel bids on eBay in the following situations: when you agree to a buyer's request, when the item isn't available anymore, if you made an error in the listing, or if you're concerned the bidder might be fraudulent.
If the auction has finished, you can contact the winner and, if they agree, you can cancel the order. You can only end auction listings with bids one at a time by selecting a valid reason.
Buyers can request a cancellation, but it's up to the seller to accept or decline the request. If multiple items were purchased as part of the same order, then all items in the order will be cancelled. An order cannot be cancelled if: The seller has dispatched the item or the item has been collected in person.
If the auction ends within 12 hours and has bids, you cannot end the listing early. If the listing ends in more than 12 hours, you can cancel the bids and then remove the listing.