How to Hide WP Accessibility Helper Admin Menus

function plt_hide_wp_accessibility_helper_menus() {
	//Hide "Accessibility".
	remove_menu_page('wp_accessibility');
	//Hide "Accessibility → Accessibility".
	remove_submenu_page('wp_accessibility', 'wp_accessibility');
	//Hide "Accessibility → Widgets Order".
	remove_submenu_page('wp_accessibility', 'wp_accessibility_sidebar_controls');
	//Hide "Accessibility → Attachments Control".
	remove_submenu_page('wp_accessibility', 'wp_accessibility_image');
	//Hide "Accessibility → Landmark & CSS".
	remove_submenu_page('wp_accessibility', 'wp_accessibility_landmark');
}

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

Where do I put this code?