In the app: Profile → Settings → Account Security → Delete my account.
Without the app: enter the email you use for Flock. If there's an account, we'll email a link that works once and expires after 30 minutes. The link only opens a confirmation page — nothing is deleted until you confirm there.
Deleting removes your profile, posts, comments, photos and RSVPs. Comments other people left on your posts go with those posts. Communities you own can be handed to a member or archived. This can't be undone. Accounts that use Sign in with Apple must be deleted from the Flock iPhone app, so Apple's access can be revoked too.