1) you'll need remove from member_uploadform.html template: <input type="text" name="remote_media_file" size="30" value="{remote_media_file}" class="input" /><br />
2) to prevent people from using modified upload form in member.php find:
$remote_media_file = format_url(un_htmlspecialchars(trim($HTTP_POST_VARS['remote_media_file'])));
Insert BELOW:
if ($user_info['user_level'] != ADMIN) $remote_media_file = "";