Disable Emoji output in WordPress.

functions.php

<?php
/**
 * Disable Emojis
 *
 * WordPress 4.2 introduced emoji JS and CSS in the page's head
 */
function prefix_disable_emoji() {

    remove_action( 'wp_head', 'print_emoji_detection_script', 7 );
    remove_action( 'admin_print_scripts', 'print_emoji_detection_script' );
    remove_action( 'wp_print_styles', 'print_emoji_styles' );
    remove_action( 'admin_print_styles', 'print_emoji_styles' );
    remove_filter( 'the_content_feed', 'wp_staticize_emoji' );
    remove_filter( 'comment_text_rss', 'wp_staticize_emoji' );
    remove_filter( 'wp_mail', 'wp_staticize_emoji_for_email' );
    add_filter( 'tiny_mce_plugins', 'disable_tinymce_emoji' );

}
add_action( 'init', 'prefix_disable_emoji', 1 );

/**
 * filter function used to remove the tinymce emoji plugin
 */
function disable_tinymce_emoji( $plugins ) {

    return array_diff( $plugins, array( 'wpemoji' ) );

}