Navigation – Remove links on items with sub categories

Hi – I have been searching for a solution but I haven’t had much luck. apparently the ‘Page Lists Plus’ does this, but I can’t see how.

I’m using the twenty eleven theme.

Basically I have a drop down navigation in the top of my site.

When I add sub categores / pages the main top nav still has a link which just goes to a blank page.

I can create a new menu manually and remove the links but this will take time so I wanted to be sure there wasn’t another option.

Also – is there a way for the sub-pages to appear in the navigation automatically as I need to add them under menus each time.

Thanks in advance.

J.