Tips on Customizing Nice Testimonials

How to Hide Nice Testimonials Admin Menus

function plt_hide_nice_testimonials_menus() {
	//Hide "Testimonials".
	remove_menu_page('edit.php?post_type=testimonial');
	//Hide "Testimonials → All Testimonials".
	remove_submenu_page('edit.php?post_type=testimonial', 'edit.php?post_type=testimonial');
	//Hide "Testimonials → Add New".
	remove_submenu_page('edit.php?post_type=testimonial', 'post-new.php?post_type=testimonial');
	//Hide "Testimonials → Categories".
	remove_submenu_page('edit.php?post_type=testimonial', 'edit-tags.php?taxonomy=testimonial_category&post_type=testimonial');
	//Hide "Testimonials → Settings".
	remove_submenu_page('edit.php?post_type=testimonial', 'nice-testimonials');
}

add_action('admin_menu', 'plt_hide_nice_testimonials_menus', 11);

Where do I put this code?

How to Hide the "Testimonial Details" Meta Box

function plt_hide_nice_testimonials_metaboxes() {
	$screen = get_current_screen();
	if ( !$screen ) {
		return;
	}

	//Hide the "Testimonial Details" meta box.
	remove_meta_box('nice-testimonials-post-details', $screen->id, 'advanced');
}

add_action('add_meta_boxes', 'plt_hide_nice_testimonials_metaboxes', 20);