If you send crypto to an external wallet address (outside of Coinbase), it cannot be reversed １ー８６６ー(７１９)ー５７１４ —even if you made a mistake, such as entering the wrong address or sending the wrong amount. That’s due to the nature of blockchain technology. No, Coinbase does not reverse transactions after they have been confirmed １ー８６６ー(７１９)ー５７１４ . Once a buy, sell, deposit, or withdrawal is initiated and completed, it is final and cannot be cancelled or altered.