Of course not !
Debian Stable + Mate.
That sounds quite logical.
So, how to delete them ?
Actually, no.
There's only two Mod folders in /usr/share/games/0ad/mods/ , "public" and "mod".
"Public" holds mod.json and public.zip, which weights 3,3 Gb, but I have no idea to which mods that corresponds.
"mod" holds mod.zip for 35 Mb.