How to Hide atec Cache APCu Admin Menus

function plt_hide_atec_cache_apcu_menus() {
	//Hide the "atec-systems" menu.
	remove_menu_page('atec_group');
	//Hide the "atec-systems → Dashboard" menu.
	remove_submenu_page('atec_group', 'atec_group');
	//Hide the "atec-systems → Cache APCu" menu.
	remove_submenu_page('atec_group', 'atec_wpca');
}

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

Where do I put this code?