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 ="[email protected]"}
Set-UnifiedGroup -Identity "GroupDisplayName" -PrimarySmtpAddress "[email protected]"
Set-UnifiedGroup -Identity "GroupDisplayName" -EmailAddresses: @{Remove="[email protected]"}