Window Manager - Reset to Default

How to reset Window Manager.

Xubuntu 12.04

 xfwm4

Ubuntu 10.04

This information is obsolete: works only with 10.04

If no window decorations appear ie:task bar, tool bars etc.

 $ gconftool --recursive-unset /apps/compiz
 $ gconftool --recursive-unset /apps/metacity
 $ gconftool --recursive-unset /desktop/gnome/session
 $ gconftool --recursive-unset /schemas/desktop/gnome/session