Go to Inspections --> Scheduled Inspections:
Identify the order from where you would like to process the refund, click on Actions --> Payments (or click the $ icon if you're using icons) to look at payments on your order.
If the credit card payment was taken directly through ISN, go to the Payment History section, look for the transaction record and click on the blue refund link:
If you have any questions about this process please let us know! You can reach us by chat, email at email@example.com, or phone at (800) 700-8112.