We are sorry to hear you go. If you would like to discontinue your account, go to Settings in the More section and tap EXIT beside Sign Out from Wallet. This will sign you out of your wallet and you can then delete the application if you wish. There is no button for the deletion of an account, however signing out does secure that no one is able to access your account as they will need the original passphrases (the ones you wrote down) to access your account; which they obviously will not have. Therefore, if you ever choose to reactivate your account in the future, this will be possible.