Open Quency and go to Settings. Delete account is the last row. Quency asks twice, and the second answer deletes the account.

Your people, their birthdays, your cards and everything you wrote are removed. Deletion happens inside the app. If you signed in with Apple, the sign-in token is revoked as part of it.

If you no longer have the app, write to hello@blufhouse.com from the address you signed up with and ask for your account to be deleted.

Some records may be kept after deletion where the law requires it. Section 16 of the Privacy Policy says what.