The truth, need help

Me and my gf talk on instagram a lot and about private stuff, like we trust each other and tell stories to each other that we thought we would bring to the grave! The problem is, her dad saw that she was dating (strict parents, no social media, internet off at this time, narcissistic) and took the phone, I tried deleting my end of the messages but I can’t do anything about what she has said and sent! I have her login info cause we give eachother our info but the problem is I don’t have her email cause it sends a code to her email, we secretly talked on a game and she mentioned getting her account taken down some how. I was wondering if anyone would help me delete the account, we need it taken down so her dad doesn’t see stuff, also discord but I changed my pfp to a girl so maybe the dad won’t think about it😭