Retirement & admission of partner

1. you have to make a deed of dessolution of partnership under registrar of assurances and pay appropriate duty for registering the same. get a certified copy of same from registrar of assurances. 

2. ,make another deed of fresh partnership and get copies of same 

3. after getting both copies apply to registrar of firm for deletion of old partner and inclusion of new partner.

3. intimate the incometax department and other departments where the firm is registered and get the registrations(s) amended.