As it’s a custom theme, it’s difficult for us to know what effect any code changes are likely to have as we have no real idea who the theme was pout together. You could try removing:
<?php wp_editor( '', 'comment', array(
'media_buttons' => false,
'textarea_rows' => '3',
'tinymce' => array(
'plugins' => 'inlinepopups, wordpress, wplink, wpdialogs',
'theme_advanced_buttons1' => 'bold, italic, underline, strikethrough, forecolor, separator, bullist, numlist, separator, link, unlink, image','theme_advanced_buttons2' => ''),
'quicktags' => array('buttons' => 'strong,em,link,block,del,ins,img,ul,ol,li,code,close')
)); ?>
from the above file but do make a backup copy first as I don’t know if the change will cause any problems.