The Hyundai Getz is the old generation model of the company in India, now as its sales going down at all time low the company has decided to discontinue with it.
The main reason behind the discontinuation is that Getz is not compatible with the new emission norms (BS-IV), and company is not interested in updating it to the new norms, due to its lowering down sales.
Hyundai Getz is the predecessor of Hyundai i20, and in other world markets company launched i20 only after discontinuing with Getz.
Every car has its product life, which depends on the designing of that product. After that time span, the design gets outdated and manufacturer discontinues the product from its range. For the same reason, Hyundai Discontinued the Getz.