If you join your devices to Azure AD in Office 365 you will at some point try to add a user to a local group on the PC and maybe need to temporarily add a user to the local administrators group.
Well as you have found out the Office 365 Azure AD user is not listed as a local user in computer management.
The local administrators group will likely only contain the local administrator account and possibly the Azure AD account used to join the device to the Azure AD in the first place.
So how do you add an Office 365 user to the local administrators group?
Fire up Command prompt by right clicking it and selecting ‘Run as Administrator’.
Enter the following command:
Net localgroup Administrators /add "AzureAD\"
You should see output similar to the image below.
Now if you look in the local administrators group you will see the users Office 365 Azure AD account!
