Once published, you cannot unpublish your site but you can hide its page.
Once you hide your pages, users will no longer be able to access them.
Click on “edit pages”:
Click the wheel on the page you want to unpublish.
Click on the option: Hide from menu
Your tab is positioned at the bottom of your list of pages and becomes grayed out.
Republish your site to enable changes
In case you want to republish your tab, select the “show in menu” option.
You can adjust its positioning in the tree structure of your menu.