How to Hide wpCMSdev Testimonial Post Type Admin Menus

function plt_hide_wpcmsdev_testimonial_post_type_menus() {
	//Hide the "Testimonials" menu.
	remove_menu_page('edit.php?post_type=testimonial');
	//Hide the "Testimonials → All Testimonials" menu.
	remove_submenu_page('edit.php?post_type=testimonial', 'edit.php?post_type=testimonial');
	//Hide the "Testimonials → Add New Testimonial" menu.
	remove_submenu_page('edit.php?post_type=testimonial', 'post-new.php?post_type=testimonial');
}

add_action('admin_menu', 'plt_hide_wpcmsdev_testimonial_post_type_menus', 15);

Where do I put this code?