To delete or cancel a “WordPress” site, go to Tools -> Delete Site in your Dashboard. An email confirmation step is required.
If you delete a site you will not be able to get it back and no one else will be able to use that site address. You must be sure you never want to use the site again if you delete it. If you are unsure, you can change the site to private and no one will be able to read it. If you decide to use it later, you can switch it back to a public site. read more