GridMarket Theme Options

Hi, I am trying to get GridMarket Theme Options to stop displaying in the admin menu for sub sites. I tried admin menu editor (changing roles, deleting the menu item, hiding the menu item) but it seem that GridMarket overrides that plugin.
How do I prevent that one line from showing in the menu so that sub sites don't fiddle with the settings? This way they can still edit the header and background menu items.