We apologize, but Airtime currently doesn’t have the option to log out.
If that’s something you’re interested in, feel free to drop us a line with your feature request. Please include details on how you’d like to use this feature.
If you need to log out of the app you can delete it from your home screen. Please note that when you decide to log back into your existing account, you will be asked to enter your phone number to receive a verification code. If you change your phone number in the meantime (and don't have a verified email address), you won't be able to log back in and will need to create a new account.
To avoid this, please make sure you have verified your email address. That way you'll be able to receive a verification code via email and be able to log back into your existing account even if your phone number changes. Please see this article on how to log back into an existing account for more info on this.