Session is built differently from regular messaging applications.
Because you are not required to sign up with an email address or mobile phone number, deleting accounts is not something we, the developers can help with or control.
To delete your account you can simply head to your main settings page and click on the 'clear data' button. You will then see an option to 'delete entire account'.
This will erase any Session related data from your local storage and from the Service Node swarm.
Once the app is deleted, as long as you don't have a copy of your recovery phrase, your Session account is unrecoverable, even by us.
To learn more about account deletion, check out this video: