Help!

Christian • Hello, my name is Christian, but I go by Cj. I have 2 beautiful babies already from previous relationships, unplanned pregnancies both are still my world! Now I am trying for baby #3! TTC 3 months!
My fiancé accidently deleted this app on his phone and just reinstalled it today, but it won't let him use his email address again because it is already used so how do I restore his information so we can be in this together?