Take notes and encrypt them using password key derivation. The password will not be stored to ensure security. When you delete the account, all notes will be deleted automatically. Moreover, when one forgots the password, it should be impossible to read the notes. In that case, it is needed to reinstall the app.
To use NoteBuddy, one must setup a simple user account (username and password with more than five chars) in order to login. All settings are stored in Android's Shared Preferences for now. The idea is to work with a SQlite database on the long term.