Without knowing what the service is, I can’t really say if that is “safe” or not.
My hunch is that there is a service running that would be better to “stop” than to end the task there (though that might work perfectly fine as well).
Out of curiousity, what happens when you go to a browser and navigate to http://localhost:80?
There are a few ideas on this page about what might be using port 80 with PID 4 -