You can control what dimensions and metrics users have access to through the Admin Console.
You can create a new Product Profile, then in the permissions tab, you can set Report Suites, Metrics, Dimensions and Tools permissions.

You can see in this example that Metrics and Dimension are set to "Auto-included" meaning everything is available.. but you can edit these and set only the items you want them to have..
Then you need to remove the old Product Profile from those users and apply this new Profile.