how eliminate canned wallpaper?

[Beartooth]

Gnome-appearance-properties gets installed with a default 
collection of wallpapers, themes, backgrounds, or whatever they're 
called; I have plenty of my own that I like better, and always delete 
those. But some screensavers, such as Slip in xscreensaver, still find 
them -- apparently in /usr/share/backgrounds. I'd like to get rid of 
them. But they seem to be protected in some way, at least against my 
userid.

Will it foul something up to the nines if I just go to the CLI as 
root, cd down as far as the bottom directories, and just use rm a/o rmdir 
on them all?

How about if I eliminate only what rm will take, and leave all 
the directories in place, but empty?

Or maybe put some of my own collection in instead?