How to refund a customer
Issuing refunds through Gumroad is - aside from the loss of money - absolutely painless. Simply go to your Customers tab, and locate your customer by searching for their email address or filtering by the product.
Click on the sale, and a receipt will slide out. Now click on Refund.
Your customer will receive an email confirming the refund, and their credit card account should receive the funds within 5-7 business days. They will no longer be able to download this product, or receive updates from you.