You know... I've been thinking of just that silvermountain. I don't run my system like that; I might have to research, document and post that too.

Great idea.

Okay coos, pertaining the themes...

via the terminal: cd /usr/share/themes, then ls, rm -r <name> where "<name>" is the one you're deleting.

So for instance, it will be rm -r Glasser to delete Glasser. Repeat but take notice that I suggest that you do not remove Emacs, default and Default (redundant, I know).

I remove all but: echo, Emacs, default and Default here.

Mind you, I'm using a different image background already from the standard Echo theme (the only theme I keep, you *should* keep one standard one as well as Diablo5) so with that said...

cd /usr/share/backgrounds and from there I remove all *.desktop except the ones I'm keeping as well as default.desktop, you'd keep default.desktop, Diablo5 and whichever you decided to keep (I keep Echo) as well as (if it's not in use) all of the *.png files.

rm *.png will kill the pngs. You have to do the desktops one by one using the rm command. Do not use rm *.desktop or else they'll all be gone and your machine will not work right.