Admin users who have rights to publish Composer pages also have the ability to unpublish pages, removing the page and any sub-pages from the public-facing side of the website. Unpublishing will present the user with a 404 error on these pages, but the page content will remain in Composer.
To unpublish a page, open the three-dot "More Actions" menu and select the circle backslash symbol. Add an optional comment in the window that pops up (so you remember why you made this page disappear) and select "Unpublish."
The status icon at the lower-right corner of the pages will now be yellow, for "unpublished."
In addition, the yellow status bar will be shown along the left side of the page tree.
Note: Admin users with publish rights to a parent page but not its child pages will not be able to unpublish the parent page.