It's really easy to cancel a bid on their platform, all you have to do is go to the item page of the item you placed the bid on and then look for the option to "Retract Bid" under the bid history section. However, it's worth noting that this option may not be available if the listing has ended or if the seller has already accepted another bid. In such cases, don't hesitate to reach out to the seller and kindly ask them if they could cancel your bid for you.