Email support@engineerphilosophy.com from the email address you signed up with (the one on your Google, Facebook or Apple account) with the subject “Delete my account”. We verify it's you and delete the account within 7 days, then confirm by reply.
Signing in with a social provider only shares your name, email and profile picture with us. Deleting your account removes all of it from our systems. We hold no other data from those providers.