Remove Domain Name from Office 365
Office 365 account is configured with domain name mustbegeek.com. To remove the domain name from Office 365, it should not be used by any users. To see if any user is using the domain name, type following cmdlet in Windows Azure Active Directory Module for Windows PowerShell. You can install Azure PowerShell module in your PC and connect to Office 365. To connect to Office 365, you can use, Connect-MsolService cmdlet in Azure PowerShell.
PS C:\> Get-MsolUser -DomainName mustbegeek.com UserPrincipalName DisplayName isLicensed ----------------- ----------- ---------- email@example.com Bipin Giri True
As you can see above user bgiri is using mustbegeek.com domain name. To be able to remove the domain name the output of above cmdlet must be empty for that domain name. Log on to Office 365. Go to Users > Active Users on the left pane. Double-click user bgiri from the users list. If you want to change domain name for multiple users then select more than one user in the users list can click Edit. In the properties page, you can change the domain name for multiple users at once.
User properties will open as shown above. Under user name, choose mustbegeek1.onmicrosoft.com domain name. This will un-assign mustbegeek.com domain name from the user properties. Click Save.
A confirmation page will open as shown below.
Click Yes to remove the domain name. In this way you can remove domain name from Office 365.