It is really easy to change a theme's name, the steps below will show you how.
Steps
These steps depend on the theme you are using. Some themes define "themesel" while most themes you will need this tutorial to change the name. The first thing is to open your "theme.php" file inside your nuke themes folder. If you use Dreamweaver or other php editors like that, this step will be easy. The idea here is to change all reference to your old theme. Let's say the theme you want to change name is "Old_theme" then you can use your find tool and find all reference to "Old_theme" and replace with your new theme's name. The next step depends fully on whether you have a "header.html footer.html and so on inside your theme folder. You will need to open all html inside that folder and do the same as in your theme.php. Find and replace all reference to your old theme's name. The last step is the easiest, now all you need to do is rename the entire theme's folder to your new one. So if your old theme's name folder was "Old_theme" then you would change it to whatever your new theme's name is.
That's all, visit the forums for more help..