How to Hide Isolation Flow Manager Admin Menus

function plt_hide_isolation_flow_manager_menus() {
	//Hide "切り分けフロー".
	remove_menu_page('isolation-flow-manager');
	//Hide "切り分けフロー → 設定".
	remove_submenu_page('isolation-flow-manager', 'isolation-flow-manager-1');
	//Hide "切り分けフロー → フロー編集".
	remove_submenu_page('isolation-flow-manager', 'isolation-flow-manager-2');
	//Hide "切り分けフロー → フロー実行".
	remove_submenu_page('isolation-flow-manager', 'isolation-flow-manager-user-1');
	//Hide "切り分けフロー → 切り分け実行履歴".
	remove_submenu_page('isolation-flow-manager', 'isolation-flow-manager-user-2');
}

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

Where do I put this code?