Get-CimInstance Win32_Process -ErrorAction SilentlyContinue |
  Where-Object {
    $_.Name -match 'act_runner' -or
    $_.CommandLine -match 'act_runner'
  } |
  ForEach-Object {
    Stop-Process -Id $_.ProcessId -Force
    Write-Host ("Stopped runner process: {0}" -f $_.ProcessId)
  }