Loop, x:\RootFolder\*.*, 0,1 ; x = drive letter - 1 = search subfolders
if (A_LoopFileDir = A_WinDir)
if A_LoopFileExt not in bmp,gif,jpg,png ; add other image extensions as needed
You can download AutoHotkey free programming tools from http://www.autohotkey.com
It may be a good idea to build in a sanity check to make sure the root folder does not contain the Windows folder or any folder with other files that should not be deleted. The code I pasted is just a quickie starting point. On the AHK site you can download tools including an IDE that can wrap the script and interpreter into an exe so that the program will run on machines that do not have AHK installed.
Edit: I added an If statement to skip to the next loop if the current folder is the Windows folder as example how it is done. The forums for autohotkey are populated with regular posters who enjoy helping people with their scripts. So just visit the "ask for help" forum there for enahancements.