Create or update a local administrator account, optionally choosing username and password.

DefineLocalAdminAccount.ps1

param([string]$username='LocalAdministrator',[string]$password='P@ssw0rd!')

$secure_password = $password | ConvertTo-SecureString -AsPlainText -Force

try {
    $LocalUserObject = Get-LocalUser -Name $username -ErrorAction Stop
}
catch [Microsoft.PowerShell.Commands.UserNotFoundException] {
    "User $($username) Not Found" | Write-Warning
}

If (!$LocalUserObject) {
    # splatting arguments to pass into New-LocalUser
    $args = @{
        Name = $username
        Description = "Local Administrator Account"
        Password = $secure_password
    }
    New-LocalUser -UserMayNotChangePassword -AccountNeverExpires -PasswordNeverExpires @args
    Add-LocalGroupMember -Group "Administrators" -Member $username
} else {
    # splatting arguments to pass into Set-LocalUser
    $args = @{
        Name = $username
        Description = "Local Administrator Account"
        Password = $secure_password
        UserMayChangePassword = $false
    }
    Set-LocalUser -AccountNeverExpires -PasswordNeverExpires $true @args
    Add-LocalGroupMember -Group "Administrators" -Member $username
}