Cancelling your account is pretty simple and straight-forward.
Just send an email to firstname.lastname@example.org or use the chat button in the app (or click here).
Just say “I’d like to cancel”, and let me know who you are! To save time, you should send it from the email account you used to sign up – otherwise, I may ask you send another email (this is so someone else doesn’t cancel your account without you knowing!). If you don’t know what account you used for your email, just ask :).