If your firm does a business of some products that can be used as by-products, you must never sell your components. If you get rid of the old stock, it may not be a very feasible option for you. Getting rid of your excess stock may not be the best option for you. In case if your firm is involved in some products that are jointly used, never sell your products. 

The later products could be used as secondary products as well. For example, if your firm is handling products like metal and steel, and the demand for cars change from smaller cars to giant ones, the demand for steel would be still there. You don’t need to sell surplus electronic components, as they may have some secondary use. 

Some better advertising or promotion techniques could also be used. Your accountants need to know your requirements and better needs of your business portal. This technique is adopted by mature companies, whose product life cycles are about to enter the decline stage. The returns or profit margins are lower and some better mechanisms are needed to save the business. 

Also you can make some other uses of uses of the old product and see what other uses it can be put to. You can also find some use of the excess components too. For example, telling a customer that ice cream syrup can not be used with hot milk, but can also be used in chocolate cakes and making chocolate icings and tasty toppings for the dessert. You can introduce a recipe which dictates this. The product demand would not decline, as estimated or forecasted.