How to delete/disable GNOME panels? (Existing solutions not working.)

There's an explanation of how to replace gnome-panel with awn on the AWN FAQ

If you have "Configuration Editor" (AKA gconf-editor) installed, run it and navigate to the key folder /desktop/gnome/session/required_components. Double-click on the key panel in the right-hand pane to edit it, and change the value to "avant-window-navigator" followed by the "OK" button. Alternatively, you can run the following command from the terminal:

gconftool-2 --type=string --set /desktop/gnome/session/required_components/panel 'avant-window-navigator'

I did this on my laptop the other day and it worked fine. As a side note, to bring gnome-panel back:

gconftool-2 --type=string --set /desktop/gnome/session/required_components/panel 'gnome-panel'

I failed completely to disable the GNOME Panel in the standard GNOME sessions on Precise (12.04). But I tried this script and it worked for me, adding a new session option on the LightDM login screen.