Menu options – header from dropdowns as opposed to a page.

As it stands I have a number of dropdown menu options with 'sub menus'. Currently the 'top level' ones, which appear in the menu bar, are 'pages'. Which are generally blank. I'd like to make it so that top link (for the pages with drop downs) are not pages themselves but merely headings which are not clickable in themselves, but which allow access to the drop down menus. You can see how it is now, looking here HMQS Gayundah If you hover over 'Galleries' you'll see the drop downs with the actual content. However if you click on the heading 'Galleries' you'll see that it's an actual page which I don't want. Hoping you can advise me how to resolve this please.