You could disable it through the plugin like Jacob suggested. Or you could use these codes to disable the emoji javascript. You need to add these codes to your theme -> functions.php file
/**
* Disable the emoji's
*/
function disable_emojis() {
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' );
// Remove from TinyMCE
add_filter( 'tiny_mce_plugins', 'disable_emojis_tinymce' );
}
add_action( 'init', 'disable_emojis' );
/**
* Filter out the tinymce emoji plugin.
*/
function disable_emojis_tinymce( $plugins ) {
return is_array( $plugins ) ? array_diff( $plugins, array( 'wpemoji' ) ) : array();
}