PHP: Remove 'WWW' from URL inside a String

preg_replace('#^(http(s)?://)?w{3}\.#', '$1', $url);

if you don't need a protocol prefix, leave the second parameter empty

$url = preg_replace('#^www\.(.+\.)#i', '$1', $parse['host']) . $parse['path'];

This won't remove the www in www.com, but www.www.com results in www.com.