You can create a refund, return, or reverse return for a particular transaction in TPE.
A refund is a request by the customer for their money after an order has been created and successfully invoiced. A refund can be initiated to give money back to the customer using the original payment information. A mark refund does not move money, but will net if configured.
A return is a request by the customer for their money from the issuer of payment (e.g., bank, credit card company) when disputing the charge of an item.
A reverse return is a reversal of the return process in which the money is returned to the merchant, often called representment.