I'll be glad to share about reversing payments, thomashall.
To stop payments made within the day, you can void the invoice or sales receipt in QBO before 3 PM PDT/PST. To do this, just click More > Void. After 3 PM, we'll process all payments, and voiding the transactions won't stop them. However, you can process a reversal in your QuickBooks Payment account. Please check this out: Void or refund transactions in QuickBooks Payments.
You may also try other options like writing them a check, giving cash, or bank transfer, depending on what's available to you. Just record them in QuickBooks as outgoing funds.
Please don't hesitate to go back to this thread if you have other questions in mind.
