Hide fileds contact user

Hi,
I would hide the fields user’s contacts in backend.

I finded this code on web, but it not works, why?

function butter_modified_fields( $contact_methods ){
	// Unset fields you don’t need
	unset($contact_methods['url']);
	unset($contact_methods['twitter']);
	unset($contact_methods['googleplus']);
	unset($contact_methods['deviantart']);
	unset($contact_methods['jabber']);

	return $contact_methods;
}

add_filter('user_contactmethods', 'butter_modified_fields');

Thanks.