Sign in to Office 365 using an administrator account.
Select the app launcher iconin the upper-left and chooseAdmin.
Navigate to Users on the left panel of the Office 365 admin center.
Click on the Display Name of the user of whom you would like to give administrator permissions.
Select Edit User Roles on the right side of the page.
Make selection of appropriate Administrative role, click on “Learn More about Administrator Roles” link to get more insight on the types of roles that are available to you.
In the Alternate email address box, type an email address that is not connected to Office 365. This email address is used for important notifications, including resetting your admin password, so the user must be able to access the email account whether the user can access Office 365 or not.
Select “Yes” to question: Do you want this user to have admin permissions to your company’s Office 365 subscription?