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You can remove a group by left-clicking on the group name, three dots, and then selecting "Remove”.
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Move Group/Units to Group
You can move a group by left-clicking on the group name, three dots, and then selecting "Move”. In a new window, you will be presented with different clusters to which the group can be moved.
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On the other hand, you can move multiple units from one group to another.
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Clone Group
It is not possible to clone a group.