Remove shutdown button on logout

[Andy Rabagliati]

Folks,

  I am doing a Thin Client lab upgrade, using the latest Xubuntu.

  I get buttons on logout, offering to shut down .. the SERVER !!

  This is not gdm - this is xfce.

  Arrgh.

  I have googled, rummaged in /etc/xdg/*, /etc/xfce4/*, /etc/X11/xfce4/*
  for something to turn it off, but I cannot find it.

  Google mutters about /usr/sbin/xfsm-shutdown-helper (not on my system)
  and /etc/sudoers (no relevant entries here) but my client can still
  hit the Big Red Button.

  I have resorted to renaming the /sbin/shutdown binary ..

  Help, please ..

Cheers,    Andy!