I hope spiky does not mind my 2 cents worth.
I can't restart or shutdown with XFCE
what display manager (login manager) are you using?
On IceWM, I installed lightdm...modified my /etc/inittab to change the line for xdm* so it reads
x:5:respawn:/usr/bin/lightdm
You may have to edit /etc/lightdm/lightdm.conf....but I have not.
I can click the icewm exit menu -> takes me to login screen and top RH corner is a power icon to
restart or shutdown.
2) there is a way of running pkexec <command> but lets keep it simple?
pulseaudio is in use
I have a different remove command with similar report.....but on your distro, its possible pulseaudio has been
autostarted or respawned.....and won't allow deletion until that process is killed or daemon stopped.
If you have time....report what you see on normal boot up for these commands, run as local user
ps -e | grep pulseaudio
pacmd list-sinks
I do not have pulseaudio installed so I get no hits....and the last command gives me
No PulseAudio daemon running, or not running as session daemon
leaping ahead....if you find it running, I would suggest delete the /etc/init.d/< daemon name>
likely to be pulseaudio reboot and then attempt delete command YMMV