Greets! I am wanting to restrict a theme only to my main

Greets! I am wanting to restrict a theme only to my main site at smdynamix.com, and not allow it for ANY membership level. I must be missing something, but I have tried to not show it as being available for any other users but myself. How would I go about doing that? In other words, I don't want users having access to the them I am using to host the main site. Thanks!