I paid an account and forgot to update my their bank info so $ went into the wrong account they no longer have access to, how can I reverse payment and be credited back?

The Community is always available to help you figure out how to reverse payments in QuickBooks Online. @ChrisMMG, thank you for reaching out to us. I'm delighted to have you in our Community forum.

It is relevant to pay accurately and track your payments. However, there are times when you may unintentionally pay transactions into the wrong account. No worries because you can reverse it through your QuickBooks Payments account. Here's how:
 

1. Access your QuickBooks Payments account by logging in.
2. Select Refund eCheck under Processing Tools.
3. Choose the date or date range for the eCheck.
4. Click on Submit after selecting the eCheck that needs to be refunded.
    

You may also want to visit this article to learn how to void or refund payments you process through QuickBooks Online: Void or refund customer payments in QuickBooks Online. You'll also be aware of when transactions can be voided or refunded.

Feel free to reach out to the Community again if you require additional help reversing your payments. We're here for you around-the-clock and eager to assist you. Have a nice day!