Hi there, Champ003.
At this time, the only way to record a refund is by the Credit Memo/Refund option in the Customers menu. Then, make a journal entry to move the funds from Undeposited Funds to the bank account, then group the journal entry with the payments to make a $0 deposit and remove the payment from Undeposited Funds.
You can check out this article for more information: Credit Memos and Refunds
I've included some links that contain three options on how to handle the credit, as well as some steps to create item discounts in QuickBooks:
Feel free to hit that Reply button if you have additional questions. Have a great day ahead.