How do I undo this?

1. Revert NGINX config by removing this from /etc/nginx/sites-available/www.baltimorenode.org:

   location = / {
       proxy_pass https://baltimorenode.github.io/temporary-homepage/;
   }
   

2. (Optionally) Remove WordPress home location:

   https://baltimorenode.org/home is provided by the https://redirection.me/ WordPress plugin, but it's not actually a redirect. It's simply configured to pass-through the location /, and because it does this at the WordPress level, it bypasses the NGINX proxy_pass described above.