Cancelation after the renewal is completed is not possible
The domain handled by Z.com is renewed directly in the database of the Registry(upper authority).
Therefore, the renewal of the registry side will be completed by the time domain renewal is completed, and the receipt of renewal fee will be also terminated by online service. Please note that any cancelation and change of renewal contents are not available.
If you do not want to renew your domain, please set the automatic renewal to OFF, via your Z.com account>>Domains.