The registered domain name is impossible to cancel. You cannot return the domain name that you have wrongfully set or given up.
You can cancel the hosting service purchased by you within a period of 7 days. The amount arising out from your return will be restored into your credit.
If you have committed an illegal act like spam, etc. with regard to the hosting service that you have purchased within 7 days, the paid-up amount will not be repaid to you and your service can be stopped and cancelled unconditionally.