Como eliminar el código html de los comentarios

Añadiendo el siguiente código al archivo functions.php de nuestra plantilla eliminaremos los elementos html de los comentarios que dejen tus lectores:

function plc_comment_post( $incoming_comment ) {
        // convert everything in a comment to display literally
        $incoming_comment['comment_content'] = htmlspecialchars($incoming_comment['comment_content']);
        // the one exception is single quotes, which cannot be #039; because WordPress marks it as spam
        $incoming_comment['comment_content'] = str_replace( "'", ''', $incoming_comment['comment_content'] );
        return( $incoming_comment );
}
function plc_comment_display( $comment_to_display ) {
        // Put the single quotes back in
        $comment_to_display = str_replace( ''', "'", $comment_to_display );
        return $comment_to_display;
}
add_filter( 'preprocess_comment', 'plc_comment_post', '', 1);
add_filter( 'comment_text', 'plc_comment_display', '', 1);
add_filter( 'comment_text_rss', 'plc_comment_display', '', 1);
add_filter( 'comment_excerpt', 'plc_comment_display', '', 1)

Espero sea de ayuda!