Recently We had faced with a specific Business scenario where the items(Finished Goods) which are obsolete (Phased Out) but still some stock exists in inventory, which gets depleted as on when sales orders are booked.The question is how to limit the ability to enter orders for only qty that <= available qty

if we made the item inactive then we can not book the sales orders for existing qty but if we uncheck only the attributes bom allowed & Build in WIP and keep customer orders enabled as checked, then the system still allows to book sales orders with qty more than the available qty.