Do you want to make a refund, but the refund button does not appear when you are on the Payment Details screen? There are several reasons for this:
The transaction has already been refunded
The payment status is not Created
You do not have the access to perform this type of operation: only the Administrator, Developer and Operator roles can refund a payment. If you were assigned the Seller role by the administrator when you created your account, you will not be able to make a refund. In this case, please contact someone who has access to finalise the refund, or ask the administrator to change your role in the Settings > Team tab.