Removing Ninja Forms Metabox from post/page edition page

functions.php

<?php
//Remove Ninja Forms Metabox
add_action( 'do_meta_boxes', 'noo_remove_metaBox_nf');
function noo_remove_metaBox_nf() {
	remove_meta_box('ninja_forms_selector', 'post', 'side');
	remove_meta_box('ninja_forms_selector', 'page', 'side');
}