Featured sites offer your users easy navigation to the most common or popular sites on the intranet. Only app managers and those granted permission can feature a site.
As the app manager, go to Sites in the left-hand navigation.
From the Featured tab, select Add/update. Type the name of the site you want to add and click it. You can add as many sites to the Featured list as you'd like.
To remove a featured site, from the same page, simply click the trashcan (remove) icon next to the site. Note this does not remove the site from the intranet, only from featured sites.