Please see Handling Refund Requests for how to process refund requests submitted by the registrant.
But, as an Administrator, you may also receive refund requests outside the system via email, phone calls, etc. In this case you can either request that the user request a refund via the system as outlined above or use the View/Edit Registration page to issue refund.
To use the View/Edit Registration page to issue the refund use the Registrations Dashboard to find the registration, click on the registration number to bring up the View/Edit Registration page for the registration. See Handling Refund Requests for details on how to complete the refund.