The first problem with the Gnome menu is that it loads the menu icons as needed causing a delay before you can see the icons. By default when you click the Gnome menu the icons are retrieved and loaded after the click (this is why there is a delay) and put in memory so they can be called later. Once the icons are in memory there will be no delay the next time you go to the same menu item. However, I think this is a bug since you should never see a delay in a menu system even if it is the first time you click on it. You can fix this problem by typing the following command as root.
From Here http://www.marksanborn.net/linux/speed-up-the-gnome-menu-and-fix-the-annoying-icon-delay/
Note: This is for Feisty (7.04)
Years ago we had a switch to do that with but that has been long gone.
You can do this with from the 'propeties' button in 'main menu' in system settings.
If you can not remove the image here you could delete the menu item you need to remove the image from and recreate it.
Or find the *.menu associated and edit that file.