Hello Raja,
There are different institutes that provide these certifications. For that, you need to attend the workshops organized by these institutes in Delhi/Bangalore. After that, they will conduct the examination and certify you.
The best method is to go for M.A./M.Sc in Psychology, and you will be certified for all the psychometric tests as an instructor or facilitator, including FIRO-B, MBTI, etc.
Thanks. Shashank