A little gist to remove any emoji reference from Wordpress.

remove-emojis-wordpress.php

<?php
/**
 *  Disabling emoji library from Wordpress.
 */
function disable_emojis() {

    // Let's remove a bunch of actions & filters.
    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' );
    
    // We also take care of Tiny MCE.
    add_filter( 'tiny_mce_plugins', 'disable_emojis_tinymce' );
    add_filter( 'wp_resource_hints', 'disable_emojis_remove_dns_prefetch', 10, 2 );
}

// Let's do this at the init.
add_action( 'init', 'disable_emojis' );

/**
* Filter funcion to remove the emoji plugin from TinyMCE.
* @param array $plugins
* @return array Difference betwen the two arrays.
*/
function disable_emojis_tinymce($plugins) {
    if ( is_array( $plugins ) ) {
        return array_diff( $plugins, array( 'wpemoji' ) );
    } else return array();
}

/**
* Removing emoji CDN hostname from DNS prefetching hints.
* @param array $urls URLs to print for resource hints.
* @param string $relation_type The relation type the URLs are printed for.
* @return array Difference betwen the two arrays.
*/
function disable_emojis_remove_dns_prefetch( $urls, $relation_type ) {
    if ( 'dns-prefetch' == $relation_type ) {
        /** This filter is documented in wp-includes/formatting.php */
        $emoji_svg_url = apply_filters( 'emoji_svg_url', 'https://s.w.org/images/core/emoji/2/svg/' );
        $urls = array_diff( $urls, array( $emoji_svg_url ) );
    }
    return $urls;
}
?>