Is it possible to cancel domain name registration/renewal once payment has been completed?

The registration or renewal fee for a domain name is non-refundable. Once payment is processed and the registration or renewal is completed, it cannot be reversed as the domain has already been charged by the Registrar/Registry. If you accidentally register the wrong domain name, it will remain in your account until its expiration date. To register the correct domain name, you will need to submit a new registration and make a separate payment.