How to use nginx to switch from port 3000 to port 80?

As I was following https://www.digitalocean.com/community/questions/remove-port-number-from-mean-js-app and I config my /etc/nginx/sites-available/default to this

server {
    listen 80 myServerName.com;
    listen [::]:80 myServerName.com;
    root /var/www/html;
    location / {
        try_files $uri $uri/ =404;
    }
}

However, when I run pm2 start app.js the website still runs on www.myServerName.com:3000. I want to get rid of :3000. How can I do that?