You can also disconnect a blog from Jetpack, which means you will no longer be able to use the functionality of that plugin on the blogs. If you’re unsure how to do that, I can do it for you. Just let me know the URL of the blog to be deleted.
Are you wanting to hide a blog from your list of blogs, or have one deleted from your WordPress.com account? If you still have access to the site, you can do either on your own. If you’ve deleted the actual site, I can remove the site from your WordPress.com list of blogs for you.