To cancel your a domain, log into your Nine Planets account and go to the Domains section. On the right-side of the line for each domain, you will see a wrench icon, click the down arrow next to that and select the Auto Renewal Status option.
On the next screen, just click the Disable Auto Renew button.
You will still receive a few email notices about the upcoming expiration as it gets closer, but the domain will be allowed to expire at the end of the current registration unless you re-enable the Auto Renewal feature.
