[K12OSN] reset gnome desktop

[Will Hatch]

hello all,

I know this has been discussed before, but I have not found the exact
instructions that will allow me to do what I want - when users either
log in or log out, I want their desktops to be reset to the default
gnome desktop.  The students are getting a little crazy with desktop
backgrounds ect.  This novice needs step by step instructions - through
gui if possible. thanks!