Not sure where you're talking about. Favorites in the Browser? Favorites in the Content Center dialog box? Need a better description of where.
Are you talking about when you RC on the ribbon and select the "Customize User Commands"
In the browser bar. In the drop down where one can select "Model", "Favorites", "Vault", etc.
If you select "Favorites", there's a drop down of groups. One of those used to be Content Center and you can add and remove groups.