From the game, at once. Menu → Account → Delete account → Yes, delete everything. No e-mail to write, no waiting.
The account with its nickname (which becomes free again), the encrypted e-mail, the linked devices, the cloud save, the scores on every leaderboard, the verified runs, the event skins, the badges and the support requests with their attachments. Deletion is immediate and final: it cannot be undone.
Data stored on your device (local progress, settings) remains yours: the game keeps working without an account. It is removed by uninstalling the app or clearing the site data in your browser. Anonymous usage statistics, which do not contain the account, are unaffected.
Write to [email protected] from the account’s e-mail (or stating the nickname): we remove everything within 30 days and confirm.