Create a local administrator account using PowerShell

Create-Administrator.ps1

$Username = "su"
$Password = "password"

$group = "Administrators"

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

if ($existing -eq $null) {

    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

}
else {
    Write-Host "Setting password for existing local user $Username."
    $existing.SetPassword($Password)
}

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

@dalexander101
You probably don't need help anymore, but specifying to only update the local account worked for me.
WMIC USERACCOUNT WHERE "Domain='$env:ComputerName'AND Name='$usr'" SET PasswordExpires=FALSE

thanks a lot it working perfectly,, I want to run this to remote servers with around 200 machines, can you please let me know how and where need to change.

clean and simple, appreciate you sharing!

lets just hope you do not deploy that script to the clients rather than remote-execute it, since the password is in the script.
There are methods to encrypt it in a script.

Thank You.
Works like a charm.