Create a local administrator account using PowerShell

Create-Administrator.ps1

$Username = "su"

# Likely needs a capital letter, certain length and a number.
$Password = "TempPassword1"

$group = "Administrators"

$adsi = [ADSI]"WinNT://$env:COMPUTERNAME"
$existing = $adsi.Children | where {$_.SchemaClassName -eq 'user' -and $_.Name -eq $Username }

Write-Host "Creating new local user $Username."
& NET USER $Username $Password /add /y /expires:never

Write-Host "Adding local user $Username to $group."
& NET LOCALGROUP $group $Username /add

Write-Host "Ensuring password for $Username never expires."
& WMIC USERACCOUNT WHERE "Name='$Username'" SET PasswordExpires=FALSE