There is no way to change the account number within TurboTax once your return is sent and accepted by the IRS. The IRS frequently asked questions link below explains that if the return has not posted to the IRS systems, there is a chance that you can call and ask the IRS to stop the direct deposit by calling toll-free 800-829-1040 during the hours of M - F, 7 a.m. - 7 p.m.
If the IRS is unable to stop the direct deposit, most likely the refund deposit will be rejected if that particular number is invalid or the account is closed. Once the IRS receives the deposit, they will send you a check in the mail to the address listed on your return.
How did you pay for your TurboTax preparation fees? If you used the Refund Processing Service to pay your fees, then you would contact Santa Barbara Taxpayer Group (SBTPG) at 1-877-908-7228 instead. The IRS will be sending your return to them first and they have your direct deposit information. They will assist you in receiving your refund.