Currently, there is not a direct method of processing a refund back to the original payment type once a credit has been generated on the invoice. The reason to this is when a credit is generated, a payment allocation is pulled from the original payment that was made and designated towards the credit created.
Refund Directly with your Payment Gateway
The refund can be processed with your payment gateway. Once you have processed the refund in your payment gateway, document the refund on the invoice in ASAP as "Other" or "Offline Credit Card" and make a note that the refund was completed through your payment gateway. This option is only available for organizations that use their own payment gateway to process transactions.
Credit Cash Out
The most common case is when a credit card was used as the original payment type when trying to refund the credit. This happens especially when say, a class has been transferred into but the new class is now cancelled. There are two ways in which this can be rectified to still issue a refund. The recommended step would be to contact your payment gateway (such as Authorize.Net, PayFlow, Bluepay etc.) directly to issue the refund. Once this has been done, you would then need to then perform a credit cash out. Here's a support article on how to perform one:
Make sure to leave detailed notes specifying the refund done through your payment gateway.
Deletion of Payment Records
The second method would require a deletion of your historical records when processing the refund. This method is not recommended as it may produce differentiating financial records when generating a new report. This however, will be able to produce the refund as requested. What you would need to do is to delete the credit for the invoice in which it was found. Use this method found in the article in order to remove the credit:
How do I change the payment method on a transaction record?
After the credit has been deleted, you can then process the refund accordingly.
We are in the process of finding a more streamlined process when handling the refunds after the credit has been generated. Please check back at a later date once a new process is built.