Dummy Top Menu item – how to?

I’m using WP version 5.6.2

I’m trying to ascertain how I can make the top menu item NOT link to anything and just the sub (child) menu items link to pages.

If you look at my site https://www.gayundah.info you can see the top menu. Hover over, for example, the menu item (Queensland’s Navy) and you will see various sub-menu options which work as usual.

The top item (on menu bar) seems to require that a page is associated with it. If you click on that you’ll see I’ve had to put a page instructing visitors to use the drop down menu. That’s not at all professional/desirable.

SO what I want to do is have the top menu item un-clickable, and only the child menu items work (as now)

I hope that makes sense and that someone can help with this.

So far I have searched in the instructions / guides and previous threads for anything relevant – but the answers that are there in previous support questions are applicable to much earlier versions of WP and don’t appear to be applicable to current versions.

In case anyone asks – I have gone into the screen options section and checked:
Advanced menu properties- Link Target, Title Attribute, CSS Classes, Link Relationship (XFN).

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