Remove a Collection-Level Group
If you have a collection-level group that is no longer being used, you can delete it. Before you delete a group, make sure that no other users or groups depend on the group for required permissions. You cannot remove the default groups at the collection-level, only custom groups.
If you removing a group in Team Foundation Server, you do not automatically remove any groups that support the collection in SQL Server Reporting Services or SharePoint Products. You must manually remove any such groups from those products.
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 a collection-level group
In Team Explorer, connect to the team project collection from which you want to remove a group.
On the Team menu, point to Team Project Collection Settings, and then click Group Membership.
In the Global Groups dialog box, select the group you want to remove, and then click Remove.
In the delete confirmation dialog box, click Yes, and then click Close.
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 Scoping a Field Rule to a Group. 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.