/usr/local/games/openarena-0.8.0$ ls
baseoa CREDITS LINUXNOTES oa_ded.x86_64 openarena.x86_64
CHANGES libogg-0.dll missionpack old_glibc README
COPYING libvorbis-0.dll oa_ded.exe openarena.exe SDL.dll
COPYING.txt libvorbisfile-3.dll oa_ded.i386 openarena.i386 WENEED
You can remove :
*.exe
*.dll
old_glibc (if you have this directory, and if you don't have an old glibc version such as the one used on Debian
Stable)
*.x86_64
OR *.i386, depends on the architecture you're on
VARIOUS TEXT FILES if they really annoy you.
You could even delete openarena.* if you don't plan to run the game as usual and stick to dedicated servers, but I don't understand well the need to clean it that much.
Do not forget to use the server fix (read other posts) otherwise clients won't be able to connect.