Due to the nature of digital currency protocols, transactions cannot be cancelled or altered once they are initiated. This is what allows merchants to accept digital currency without the risk of chargebacks.
Can I withdraw from Blockchain to my bank account?
Yes, it’s the only way. You can’t “withdraw” bitcoins into your bank account, any more than you could “withdraw” a car into your bank account. You have to sell them in exchange for money, and then you can deposit the money in your bank account.