PayPal's support page details the steps required to issue a full or partial refund.

Please keep the following points in mind when issuing a refund:

• PayPal may require sellers to cover the PayPal seller fee when issuing a refund, as per their policies. As a result, sellers may have to add funds to their PayPal account prior to issuing a refund.
• Always reach out to PayPal support for assistance if you experience any problems when issuing a refund.
• Always inform the Swappa support team on your private sale page or by using our help desk whenever a refund is issued.