If you have a lot of Windows 7 themes, but you frequently delete them, you can use this AuthotKey script to mass delete them with one key combo.
1. Step Download and install AutoHotkey, website is http://www.autohotkey.com/
2. Step Open the AuthotKey.ahk and insert the text below. You can edit the Autohotkey.ahk by right-clicking on the Authotkey icon in your system tray:
FileRemoveDir, %USERPROFILE%\AppData\Local\Microsoft\Windows\Themes\, 1
3. Step Then right-click on the system tray icon and and click on Reload This Script
4. Step You can now mass delete Windows 7 themes from the CP using the shortcut CTRL + ALT + d
What the script does it remove the directory where the themes are stored e.g. C:\Users\sOliver\AppData\Local\Microsoft\Windows and then creates a new folder (FileCreateDir) again.
You can play around with this script to do whatever you want with your themes.
Of course you can easily delete the themes manually, but I find it quite handy to have shortcuts for simple tasks. You could even create a list of shortcut and pin it to your desk, so that you can get mundane tasks done in a matter of seconds.