Is it possible to change the main site?

I want to change the main site for my multi-site installation. Basically site #1 uses URL mysites.com.
Site #10 uses URL blog.mysites.com. I want site #10 to be the main site and respond to the URL mysites.com. I want to remove site #1 from the installation.

I've changed URLs for sites, but I've never messed with the main site. I want to make sure it will work before I make any changes.

Thanks.