How to Use
Download > Install > Activate. That’s it!

Example
Once activated, the default website field on WordPress post comments will be removed. Discourage backlink spam attempts by not providing the option. Scroll down to this post’s comments and you will see the website URL field has been remove.

Source
This code can be pasted into the functions.php file of your child theme or, download and install the plugin for simple code activation.

function viawebs_plugins_remove_website_url ($fields){
    if(isset($fields['url']))
       unset($fields['url']);
       return $fields;
}
add_filter('comment_form_default_fields', 'viawebs_plugins_remove_website_url');