How do I force logout of an app that I signed in with my Google account?

I downloaded an app for 18+ years old that I had used on a different device and I thought I had used Google oAuth, so I selected that option to log in with. When I realized it was incorrect, I didn't see anywhere to sign out, so I put down a birthday as if I was 8 years old, hoping that would log me out, but it didn't. Now when I open the app it just says you need to be 18 years old to use the app and doesn't have an option to log out. I tried the following to get logged out of the app, but none have worked: * Deleting the app data and cache * Uninstalling and reinstalling the app. * Restarting the phone * Removing the connection from [Google Third-party apps & services](https://myaccount.google.com/connections) So where on my device is this login actually stored? How can I remove it?