1. Navigate to and sign in to Office 365 with your admin credentials.
2. Navigate to Admin center.
3. In the left panel, expand Users and click Active users. Check the box next to the user who you want to assign/unassign admin roles and click Edit on the Roles row.
Note: Check boxes of more than one user if you want to assign/unassign admin roles for several users at once.
4. In the Edit user roles pane, select the option correspondent to the role that you want to assign to the user.
Note: Choose Customized administrator to see a list of customized roles. For a description of each one, click on the link Learn more about administrator roles.
5. At the bottom left, choose Save.