In order to log out of your app, simply close the app fully and ensure it is not running in the background. If you are unsure how to do this, please see the two articles below for iOS and Android respectively.
https://support.apple.com/en-us/109359
https://support.google.com/android/answer/9079646?hl=en#zippy=%2Cclose-apps
Your app will also automatically log out after 10 minutes of inactivity.