【If your mobile number does not change】
If your two factor authentication is set as your mobile number, you will not need to change anything.
If your two factor authentication is set as Google authentication, on the security page change two factor authentication from "Google" to "mobile number". From the next login, you will be able to login via SMS authorization code.
【If your mobile number changes】
Please contact customer support through the inquiry form. We would release your Google 2-step verification after the identity confirmation.