How do you solve existing user problem if the login method change email base login to OTP based login,

there are already user in the system who login with their email or social. now if we get rid of social and email login - signup, how the existing user will login again.

Provide 2 options through which a user wants to login

  1. Login through email OTP – he has to enter the OTP sent to his email ID once he selects that optionn.
  2. Or mobile OTP – he has to enter the OTP sent to his mobile(if at all it was taken while registering)