From the menu bar, choose Processing Tools, then Reverse a transaction.
Locate the transactions you want to reverse.
Select the transaction(s) you want to reverse from the list and then click Submit.
Please be reminded that transactions processed in online cannot be downloaded to QuickBooks. To keep your QuickBooks Online accounts up-to-date, you'll need to enter a reversal manually. To reverse the amount you can create an offsetting refund receipt (if this is a payment), or an offsetting sales receipt (if this is a refund).
Click the QuickBooks Plus icon.
Under the Customers section, choose Refund Receipt.
Enter the refund information then click Save and close.