My height 6'2".my age 22 years old.i want to decrease my height 6".how it is done?

No can do!: Unfortunately there is nothing you can do to decrease your height, although when you become elderly you may lose an inch or twp of height due to spine aging.

Unusual request: Most want couple inches longer than they are , technically is possible to shorten by cutting off 2 " of your long bones of both legs . First very few orthopedic surgeons are willing to do second very few centers will promote this kind of service