[rosede]

What is the correct syntax to clean out only the Thumbnails and not other cached images?

The "prune" command texturecache.py P would automatically remove cached images that are not referenced by a movie, tvshow or album/song/artist, from your media library.

However your biggest problem is that you're sharing a single texture cache between multiple clients, which is generally a bad idea.

Are all your clients using a centralised MySQL database for the media library? If not, then each client is likely to have a different view of the texture cache, and purging the cache based on the media library from one client is likely to cause issues for your other clients that have different media libraries as they suddenly lose access to movie/tv/music images (now deleted) that they have cached. 

Yes, I am using MySQL to share the media library.  

So will the purge clean out only the Thumbnails?  I don't want it deleting fan art and other images.  

If I change the location of the Thumbnails back to local storage, can I use texturecache.py to regenrate those thumbnails?   

Thanks

Daryl