what is ramp down in product line and how to handle ramp down in all stage of product line ?

I take it its built around the concept of production ramp down?
What it is is a response to a prediction in slowdown demand. The firm anticipates slowed sales and has to decrease production to match the decrease in demand.

In regards to product ramp down, it might be important to divert sales resources to other products, or eliminate positions (layoffs, hiring freeze, etc...). In regards to production, raw materials but also decrease, inventory should be reexamined, production employment should meet the same fate above as salespeople, and in regards to the investment capital, ROI's must be analyzed to determine the next best return opportunity.

Hope that helps, and I can contribute more if you'd like.