Yes, you can withdraw the offer you have made at any time - as long as the transaction has not yet taken place. All you need to do is notify the seller and they will be free to sell the item in question to another potential buyer. If you have already paid for the item, the process can get a bit trickier, and negotiating a refund will usually take a couple of messages back and forth between you at the other party involved. If you are unable to reach an agreement, the representatives of 5miles can always step in to resolve the issue.