How to: Remove Users from a Server-Level Group
When users or groups are no longer part of the team project or no longer need access to team project resources, you can remove their user account from the server-level group.
Server-level groups must have at least one user or group member in order to be valid. Therefore you cannot remove the last remaining member (user or group) from a server-level group. If you want to remove the one remaining member of that group, remove the server-level group from Team Foundation Server.
To perform this procedure, you must be a member of the Team Foundation Administrators group. For more information about permissions, see Team Foundation Server Permissions.
To remove users from a server-level group
In Team Explorer, select the Team Foundation Server that the group is in.
On the Team menu, point to Team Foundation Server Settings, and then click Group Membership.
In the Global Groups dialog box, select the group from which you want to remove users, and then click Properties.
In the Team Foundation Server Group Properties dialog box, on the Members tab, select the users or groups you want to remove.
When you completely remove a user or group from Team Foundation Server, any rules specifically and only for that user or group will also be removed. For more information about rules, see Conditional Field Rule Attributes. Those rules will no longer apply if you re-add that particular user or group. You must re-import the work item type that contains the rule specific to that user or group. For more information about importing work item types, see How to: Import a Work Item Type to an Existing Project.