CmdID / PowerShell / Cmdlets / Remove
Remove-MailUser
Use the Remove-MailUser cmdlet to remove existing mail users. Exchange PowerShell reference
From the Exchange PowerShell reference 7 parameters Its page in the reference
Parameters
-IdentityThe Identity parameter specifies the mail user that you want to remove.-Confirm, -cfThe Confirm switch specifies whether to show or hide the confirmation prompt.-DomainControllerThe DomainController parameter specifies the domain controller that's used by this cmdlet to read data from or write data to Active Directory.-IgnoreDefaultScopeThe IgnoreDefaultScope switch tells the command to ignore the default recipient scope setting for the Exchange PowerShell session, and to use the entire forest as the scope.-IgnoreLegalHoldThe IgnoreLegalHold switch ignores the legal hold status of the user.-PermanentlyDeleteThe PermanentlyDelete switch immediately and permanently deletes (purges) the mail user, which prevents you from recovering or restoring the mail user.-WhatIf, -wiThe WhatIf switch shows what the command does without making any changes.