Cannot Delete Plugin Folders

Windows Server 2008 R2.

I have seen this problem posted before. But none of the suggestions are working for me. I installed a plugin called “User Access Manager,” didn’t like it, deactivated it, then tried to delete it. I was told that the folders could not be deleted. When I login as a system administrator to the server on which the web site (and plugin folders) exists and try to delete the folder I get the dialogue:

You require permission to IUSR to make changes to this folder

I went in and changed the folder owner to the account I am using and it still will not allow deletion. Moreover, I cannot change the folder owner for the three subfolders contained in this plugin folder. What else can I do to get RID of this folder???