A user should be able to right-click on a manual group.
The user will have to right-click on the group on the LHS of the UI and click on the delete group option. The user should be presented with a confirmation dialog before deletion takes place.
Upon successful deletion, the selection in the LHS should move to next group above in the list and the RHS view refreshed to match the new selection.
The root group can never be deleted.
If the group has been granted some role over some other group, then these roles are also lost in the deletion process.