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
Sync updates to Novi (optional)
To see the Refund Receipt in Novi without waiting for the next scheduled sync, you can manually trigger a sync from the Member dashboard on the backend. This will bring over any changes made in QuickBooks Online.