Email happydead313@gmail.com from the Google account you signed in with, with the subject "Delete my SOS Beacon account". It will be deleted within 30 days.
Your profile (name, birth month and year, last location), every alert you sent, your family-group membership, your blocked list, and your sign-in account. Nothing else is kept afterwards, except reports you sent about other people's alerts (kept for the administrator's safety review) and where the law requires it. Emergency contacts and medical info were only ever on your phone; deleting in the app erases them too, and uninstalling the app removes them.