Settings → Delete account & data → Delete. This is immediate and removes your account, everything you asserted (names, birth years, photo claims), your uploaded photos, your invites and your push tokens.
Email hello@illsn.xyz with the subject "Delete my Roots account", from the email address linked to your account (or include the name you used and any invite link you have, if your account was never linked to an email). We complete deletion within 30 days.
Not using the app but someone added you? The same email gets any profile about you removed.