Your domain name belongs to you until your registration expires, even if you cancel your plan.
If you registered your domain through Yahoo!, and you decide to cancel your plan:
If you used a domain you previously owned with your Yahoo! plan, and you decide to cancel:
Tip: If you choose not to renew your domain name when it expires, someone else may be able to buy it!
If you're going to cancel your plan, be sure to make arrangements for your domain name first. Sign up for our basic Yahoo! Domains plan, which will allow you to continue managing your own domain with your Yahoo! tools, or transfer your domain to another provider.