Code:
gconftool-2 -s -t list --list-type string /desktop/gnome/session/required_components_list [filemanager,windowmanager]
gconftool-2 -s -t string /desktop/gnome/session/required_components/panel ''
That will remove the panel from the required components list, and blank out the default panel to use.
For a graphical editor, try gconf-editor, if you don't have that command just install it with yum.