How to hide text format options when using WYSIWIG module?
Try unsetting the field elements. According to the blog post this kills TinyMCE

&lt;?php
  function [theme_name]_form_comment_form_alter(&amp;$form, &amp;$form_state, $form_id)
  {
    $form['comment_body']['#after_build'][] = 'remove_tips';
  }

  function remove_tips(&amp;$form)
  {
    unset($form['und'][0]['format']['guidelines']);
    unset($form['und'][0]['format']['help']);
    return $form;
  }
?&gt;


source: technonaturalist