How to Hide NS GDPR Helper Admin Menus

function plt_hide_ns_gdpr_menus() {
	//Hide the "NS GDPR" menu.
	remove_menu_page('ns-gdpr/ns-admin-options/ns_admin_option_dashboard.php');
	//Hide the "NS GDPR → NS GDPR" menu.
	remove_submenu_page('ns-gdpr/ns-admin-options/ns_admin_option_dashboard.php', 'ns-gdpr/ns-admin-options/ns_admin_option_dashboard.php');
	//Hide the "NS GDPR → Join the NS CLUB" menu.
	remove_submenu_page('ns-gdpr/ns-admin-options/ns_admin_option_dashboard.php', 'join-the-club');
}

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

Where do I put this code?