Hide Pages from the Navigation Menu
To a hide a page from the navigation menu, go to the Pages tab.
Select the page and check the Hide in Navigation option shown there.
Taking this action with a page means it won't show up in the navigation menu. As seen in this example, the hidden page named "Thank You" is nowhere to be seen.
How would a visitor find a page if you hide it from the navigation?
You can create links to pages using text, images and buttons within the content area of your site. So you can create a link to a hidden page from elsewhere on the site instead of from than the navigation menu.
But why hide a page at all?
If you have dozens and dozens of pages, showing all those pages in the navigation could be overwhelming for your visitors. Hiding some of the less important pages and linking to them from the content area of your site is a way to keep the navigation area clean and easy to, well, navigate.