There is actually no "connection" needed in Andaman7: your data is saved only in the application on your device. If you delete the application, you also delete all your medical data.
If you wish to protect your information further, you can go into the settings to activate a password for when the application starts.
If you wish to log out or change accounts, you can uninstall the application and reinstall it, this will bring the application back to its original state. You will no longer have any medical data related to your first account. Your data is also not stored on our servers.