How do you remove MariaDB and NGINX from Mac via terminal?
Trying stopping the process - nginx -s stop should shut the server down. To restart it,  run which nginx to tell you where it's running from. Then run the main executable.

Instead of going for the nuclear option of removing it straight away, stop the server. Once you know where it's starting from, you can navigate there and look at the config files to see what port it's on etc. Or you could just nuke it using rm -rf on the nginx paths.