Hi Chuck

i also had this same issue, i finally came across a solution that worked for me... maybe it will word for you as well.

I made sure that non of my skins of containers were uses by DNN. i then proceeded to delete the containers and skins from my windows server: locations = Portals\0\Containers and Portals\0\Skins. 

i then opened my DNN site and also deleted the skins and containers form the Admin> File Manager.

i then cleared the cache and restarted the application from Host> Host Settings.

after this i opened File Manager , ticked the check box and clicked on Synchronize Files.

this is how i was able to delete my skins forever... hope this helps