What OS are you running this on?
How did you install mosquitto?
If you already have mosquitto installed and running, why do you want to also use Mosca?
…cause i trie to communicate with Node-red from my Pi and the node red from my Windows PC. And all my tries to fix this with mosquitto are just with out a result, so I tried to fix it with Mosca cause it seems beeing easier with mosca and node red…
You asked how to delete mosquitto, which Colin answered. You didn’t say you needed both mosquitto and mosca to be running at the same time.
If you truly want them both running, then you’ll have to configure one to use a different port - they cannot both use 1883.
But if you’re already using mosquitto, I don’t see why you’d need mosca at all. You haven’t said what issues you had with mosquitto and node-red - maybe that’s the thing to solve here.
The error you have is because port 1883 was already in use, so take a look deeply and chechk what you have, maybe you have configured incorrectly on node red and you have now some instance with booth configured on same port, try to stop for a moment mosquitto and check if node red start with “sudo service mosquitto stop”.
Yes, netstat. But actually I agree with Nick, work out what the problem was with mosquitto and sort that. Most using MQTT on a pi use mosquitto so you are more likely to find support with that than another broker I think.