How to remove menu items?

I want to remove these items from the System menu:

• Help and Support
• About Gnome
• About Ubuntu

I can't do this with Main Menu (bad naming, should be menumanager or so).

One way to do this is to simply rename three files. Run these commands in a terminal:

cd /usr/share/applications
sudo mv gnome-about.desktop gnome-about.desktop.bak 
sudo mv ubuntu-about.desktop ubuntu-about.desktop.bak
sudo mv yelp.desktop yelp.desktop.bak

To add them back to the System menu:

cd /usr/share/applications
sudo mv gnome-about.desktop.bak gnome-about.desktop 
sudo mv ubuntu-about.desktop.bak ubuntu-about.desktop
sudo mv yelp.desktop.bak yelp.desktop

I was looking at the gnome-panel source code and it seems these three items are hardcoded to be included in the System Menu, but if the applet can't find those .desktop files with those exact names they won't be added.

Here is what the System menu looks like after renaming those files:

You can try sudo apt-get purge yelp, it will remove Help and Support.