Deleting permission groups does not delete individual users.
To delete a group
In the Administrator, connect to the server, then click the Server tab.
Select the Group you want to configure from the left-hand navigation tree.
In the left pane, right-click the Group you want to delete, then click Delete. A confirmation message appears.
Click Yes. The users in the deleted Group retain membership in any other of their assigned Groups and the All Users Group.