How to add an office 365 user as an Admin
Use the Start Menu
You can open an administrative Command Prompt using just the Start menu (or Start screen in Windows 8). Hit Start, type “command,” and you’ll see “Command Prompt” listed as the main result. Right-click that result and choose “Run as administrator.”
When you launch the Command Prompt with admin privileges, you’ll likely see a “User Account Control” window asking for permission to continue. Go ahead and click “Yes.”
Once you’ve got the “Administrator: Command Prompt” window open, you can run any command, whether it requires administrative privileges or not.
Enter the following command:
Net localgroup Administrators /add "AzureAD\<users office 365 email address>"
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