Greeting.

Recently, my manager decided to move his career to other company.
So we need to change the admin address from Sam.k@com2us.com to jhan@com2us.com.
But I don't know how to change admin as like below.

without any compilations, the best way is that just change account admin ( From Sam to Jun)

Can you please let me know how to do that.
or if that is not possible, please let me know too which way is best for us.

Thank you.
Best Regards
Jun Han