If a customer has made a payment to your organization using QuickBooks Payments, you can issue a refund from the QuickBooks Payments Merchant Center.
There are multiple ways you can do this within the QuickBooks Payments Merchant Center. This QuickBooks Help Article will walk you through the steps:
Void or refund transactions in QuickBooks Payments
When issuing refunds from QuickBooks payments, you may also need to create a manual refund receipt on your members account in QuickBooks Online to reflect that refund. Here is a video going over the refund process (hint: Skip to the section that says "Refund receipt ays "Refunds for goods or services that didn't satisfy the customer". the process is similar for Novi customers!)