Windows 7 - Explorer.exe using unapplied themes, why?

I was trying to delete some third-party themes from the themes folder, but when I try to delete their respective folders, windows tells me that the Windows Visual Styles files are being used by something. I used procexp.exe to find out what, and apparently they're being used by explorer.exe. Why would explorer.exe be using these files, and how would I delete the files?

First , in the personalization window, right click on an installed theme > delete theme.

Then Delete the respective folder and .theme file in C:\Windows\Resources\Themes.

EDIT : The theme you are deleting must not be the theme currently applied .

Be sure you are using the default aero theme then logoff/logon then try to delete that 3rd party theme.
Jerry

Logging off worked. Probably just needed to restart explorer. Thanks for the help.

You're Welcome good to hear you got it.
Jerry