How to prevent certain bundled CKEditor plugins from loading
We can disable CKEditor plugins by following hook as show with the example for disabling image and image2 plugins:

/**
 * Implements hook_ckeditor_settings_alter()
 */
function MYMODULE_ckeditor_settings_alter(&amp;$settings, $conf) {
  // Comma separate names of plugins to remove.
  $plugins_to_remove = 'image,image2';
  $settings['removePlugins'] = !empty($settings['removePlugins'])
    ? $settings['removePlugins'] . ',' . $plugins_to_remove
    : $plugins_to_remove;
}


(taken from my own article: http://kb.detlus.com/articles/drupal/drupal-7-disable-ckeditor-bundled-plugins/)