You can move a cluster from one group to another in the main window's nodes area.
To move a cluster:
Select Move Node from the option menu.
Click in the Group field and type the name of the group the cluster is to be moved from, or choose the group from the drop-down list. If you choose a group that does not contain the cluster, the cluster is not moved.
Click in the Node field and type the name of the cluster to be moved, or choose the cluster from the drop-down list.
Click in the Move to Group field and type the name of the group the cluster is to be moved to, or choose the group from the drop-down list.
Click on Apply or OK.