I wish to redirect all traffic from world wide web.mydomain.com to mydomain.com, even if there's a particular path (like world wide web.mydomain.com/article)

Can One do that through my domain registrar or does it need to be achieved around the server?

It can be done with simple url spinning :

<IfModule mod_rewrite.c>

  RewriteCond % !=on

  RewriteCond % ^www.(.+)$ [NC]

  RewriteRule ^(.*)$ http://%1/$1 [R=301,L]

</IfModule>

(on apache)