@JotikaT2 and @Anonymous are both correct in this matter - once you have filed your return with payment information (bank routing number, account number, payment amount and payment date), you cannot change any of that information. It is processed automatically and, for numerous security reasons, cannot be modified.
TurboTax transmits your return (including payment information) to Maryland. Once it is sent (by you), TurboTax cannot change any of it.
Once MD receives the return via e-filing, they cannot change the payment data.
From the Maryland Department of Revenue's Making Direct Debit Payments:
"Enter Numbers Carefully
Enter your bank account and routing numbers carefully. We cannot change any of your numbers after you have entered the information, even if you request us to do so. In addition, we cannot cancel your direct debit payment after you have authorized the payment."
