A deposit was credited to my account by mistake. Does the bank have to get my permission before removing the funds?
No. If the funds are credited to your account in error, the bank doesn't need your permission to remove funds. The bank may correct the error by exercising its legal right of off-set. This right allows a bank to charge the account for a debt owed to the bank.
To correct this error, the bank must remove the funds from the account and deposit them into the correct account.