Do you mean, that like you created island and like you are leader? But you don't want to be as leader, so you want to pass down leadership to some of ur friends? If so, there aren't any leaders at all.
There are leaders actually - they have the power to kick people, etc. So...I'm pretty sure the command was /coop leader (someone) or alternatively, if you leave the coop, the leader will change to the oldest person that joined the coop & they can add you back. Correct me if I'm wrong.
The easiest way is to have the leader leave the coop. The leadership will then pass on to the first person they invited in the coop that's still in the coop (hasn't left yet). If that person who assumes leadership is not the person whom you want to be leader then repeat till the person whom you want to be leader is leader. Make sure to have your inventory empty before leaving the coop as leaving a coop clears the inventory. Using the /coop leader command is finiky and I've heard some instances where it didn't work
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