You may want/need to run Xfce without giving the user access to a panel; this may seem impossible at first sight, as xfce4-panel is a dependency of the xfce4 package.

This can be solved by a simple work-around; as root save the original xfce-panel file

   # mv /usr/bin/xfce4-panel /usr/bin/xfce4-panel.bak

and create a new /usr/bin/xfce4-panel file that contains the two lines:

   #!/bin/bash
   exit 1     

not forgetting to chmod it to a+x

The process may need to be renewed in the future whenever xfce4-panel gets updated.