How to remove someone's google account off my phone when asked to verify

We are going through custody battles atm, and I allowed my child to take her phone to her mother's, in case she needed me or felt unsafe. Her mom took the phone, removed my google account, added hers and make it to where it needs to verify the account before I can make any changes. So now she can control all the parental locks, send messages when she shouldn't be, ect. How can I remove her account and replace mine since they are my phones to begin with?