modify-tinymce-editor-to-remove-h1.php

<?php
/**
 * Plugin Name:  Remove H1 Format
 * Plugin URI:   http://calliaweb.co.uk/modify-tinymce-editor/
 * Description:  A simple plugin to remove the H1 format from the WordPress TinyMCE editor.
 * Version:      0.0.1
 * Author:       Jo Waltham
 * Author URI:   http://calliaweb.co.uk/
 * License:      GPL-2.0+
 * License URI:  http://www.gnu.org/licenses/gpl-2.0.html
 */

// Exit if accessed directly
defined( 'WPINC' ) or die;

if ( ! class_exists( 'Remove_H1_Format' ) ) :

class Remove_H1_Format {

	function run() {
		add_filter( 'tiny_mce_before_init', array( $this, 'tiny_mce_remove_h1' ) );
	}

	/*
	 * Modify TinyMCE editor to remove H1.
	 */
	public static function tiny_mce_remove_h1( $init ) {
		//* Allow developers to conditionally short-circuit the plugin.
		$pre = apply_filters( 'tiny_mce_remove_h1', false );

		//* If the plugin has been short circuited, do nothing.
		if ( ! empty( $pre ) ) {
			return $init;
		}

		// Add block format elements you want to show in dropdown
		$init['block_formats'] = 'Paragraph=p;Heading 2=h2;Heading 3=h3;Heading 4=h4;Heading 5=h5;Heading 6=h6;Address=address;Pre=pre';

		return $init;
	}

}

endif; // End class exists check.

//* Handy function for grabbing the plugin instance
function jw_remove_h1_format() {
	$plugin = new Remove_H1_Format;
	return $plugin;
}

//* Get the plugin running.
jw_remove_h1_format()->run();