Open wp-comments-post.php in wordpress root directory and edit it.


Search for this line

PHP Code: 
$comment_author_url   = ( isset($_POST['url']) )     ? trim($_POST['url']) : null; 
Remove it and save the file (dont close the file yet) and recheck the post to see if url option is gone from there If all is done, close the file, if no or anyshit happens, again add that line there and save again.






Ah, same things said above aswell

Just search for term "Website" in comments.php in theme folder and remove the subsequent code and save it