Suppress navigation on a top-level menu item

I have a number of two-level menu items on my page. I would like to suppress any navigation action on the top-level menu item when there are sub-menu items, so that only the sub-menu items go anywhere. Is this possible? (I am using the free version of the Alante theme)

Thanks!

Cbeebie

The page I need help with: [log in to see the link]