Hi Toby,

It kind of depends on whether you are using a single-site or multi-site system. In a single-site system the "Content Administrator Privileges" allows Content Administrators the option to add and remove users in addition to their other privileges. In a multi-site system, this functionality is disabled and only system administrators can add and remove users.

The logic behind this setup is that, on a multi-site system, a particular user can belong to multiple sites, with different user rights and license levels on each site.  This setup makes the user list a list with system-wide application rather than a list that effects only a particular site.   Anything system-wide is controlled by the system administrator, while content administrators are tied to a particular site.  Content administrators in multi-site systems can still manage groups, projects, workbooks, and data connections within their site.

If a particular user needs the privileges to add or remove users, this user can be made a system administrator.  There is currently no way to allow a content administrator to add or remove users on a multi-site system.

Hopefully this provides some insight for you!

-Tracy