Change Office 365 Group Email Address Using PowerShell

First you need to log into your admin account with PowerShell

Set-UnifiedGroup -Identity "GroupDisplayName" -EmailAddresses: @{Add ="GroupName@example.com"}
Set-UnifiedGroup -Identity "GroupDisplayName" -PrimarySmtpAddress "NewGroupName@example.com"
Set-UnifiedGroup -Identity "GroupDisplayName" -EmailAddresses: @{Remove="GroupName@openbayes.com"}