$Service = Get-Service -Name iperf3server -ErrorAction SilentlyContinue

if ($null -eq $Service) {
    Write-Host "Service is not installed"
} else {
    & "C:\Program Files\nssm\win64\nssm.exe" stop iperf3server
    & "C:\Program Files\nssm\win64\nssm.exe" remove iperf3server
}