CSS code to hide one navigation button and certain pages

Site URL: https://www.artthou.co.uk/

Hi Square space community - I'm looking for CSS code, to be able to hide a specific navigation button on specific pages (not all pages). 

So in my instance the navigation button is "Viewing Rooms" I would like it to be hidden/removed for my member only pages and be visible on the public pages. Any tips / thoughts are appreciated. 

Thanks, Hugo