Simplify WordPress TinyMCE

functions.php

<?php 
/* Simplify the default tiny MCE */
add_filter( 'mce_buttons', 'wpcustom_mce_buttons_1' );
function wpcustom_mce_buttons_1( $buttons ) {
  $buttons = array( 'styleselect','bold', 'italic', 'bullist', 'numlist', 'alignleft', 'aligncenter', 'link', 'unlink', 'pastetext', 'removeformat', 'undo', 'redo');
  return $buttons;
}

add_filter( 'mce_buttons_2', 'wpcustom_mce_buttons_2' );
function wpcustom_mce_buttons_2( $buttons ) {
  $buttons = array();
  return $buttons;
}

/* 
 * Add new styles to the TinyMCE "formats" menu dropdown. These should match your editor-styles.css and front-end stylesheet.
 */
add_filter( 'tiny_mce_before_init', 'wpcustom_styles_dropdown' );
function wpcustom_styles_dropdown( $settings ) {
  unset($settings['preview_styles']);
  $new_styles = array(
    array(
      'title' => 'Headings',
      'items' => array(
        array(
          'title'     => 'H3',
          'block'    => 'h3'
        ),
      ),
    ),
    array(
    	'title' => 'Paragraphs',
    	'items' => array(
    		 array(
          'title'     => 'Paragraph',
          'block'    => 'p'
        ),
        array(
          'title' => 'Callout',
          'block' => 'p',
          'attributes' => array('class' => 'callout')
        ),
    	),
    ),
  );

  // Don't merge
  $settings['style_formats_merge'] = false;
  $settings['style_formats'] = json_encode( $new_styles );
  return $settings;
}