On your old server, you should see a Roon icon in the task bar on the right. If you right-click on this, it will give you an option to quit the server. See image below:
Once you quite the Roon Server application, you should then be able to uninstall it without issue.
Also, once you have installed Roon on a new computer, if you want to play music on the computer you have to enable the audio endpoint in the Roon → Settings → Audio settings page.
You don’t need to delete Roon server or Roon client from your old computer. Keep it as a backup in case something happens with your new Roon server. You may also want to use the old computer as a Roon client controlling your new Roon server.
With one Roon license you can have multiple Roon servers, but only one authorized at a time. When you authorize the server you want to use, Roon will ask you to unauthorize the server(s) you don’t want to use. But it will still work as a Roon client because there are two different Roon programs on each computer.
You are right clicking the Roon Server launcher on the Desktop. What you should be right clicking is
the Roon icon in the Windows task bar on the right bottom corner of the screen, where Windows places e.g. the volume button
I don’t have Roon there (see photo)
It was enough to shut down the first computer!
But the problem now is that the first computer, the one where the Roon server is basically disabled, still works after reboot, I can listen to different songs simultaneously, it is independent of the new one, so I have two entirely independent Roon. It’s going to crash…
Roon server is running on one computer and Roon client is running on two computers. That’s normal if you open both clients. Go to Roon - Settings - General on both computers and you’ll see they are referring to the same server that is authorized.