$regPath = "HKCU:\Software\Microsoft\Office\16.0\Common\MailSettings"
$mailSettings = New-Item -Path $regPath -Force

Set-ItemProperty -Path $regPath -Name "DisableSignatures" -Value 1

$regPath2 = "HKCU:\Software\Policies\Microsoft\Office\16.0\Common\MailSettings"
$mailSettings2 = New-Item -Path2 -Name "DisableSignatures" -Value 1
Rename-Item -Path "$env:userprofile\AppData\Roaming\Microsoft\Signatures\Signatures" -NewName "Signatures-old"