There's no need to disable it, because the restarted will automatically stop trying to restart it as soon MSFS 2020 quits. So, your problem doesn't have anything to do with GSX or Couatl and, instead, is that MSFS 2020 is still running.
You can verify this is the case if you terminate Flightsimulator.exe from the Task Manager: you'll see both Couatl and the restarter will exit automatically.