Account settings has a new Delete account page, on the website and in the mobile app. Deleting ends every sign-in and erases your email address, name, handle, bio, photo, password, two-factor setup and linked Apple, Google and LinkedIn accounts. Teams you own alone are archived; what you wrote in teams that continue shows as Deleted user.
The account is not deleted while you own a team with other members, or while a Magpie plan or a supporter subscription is still set to renew. The page says which applies. You confirm with your password, plus a two-factor code if that is on, or by typing DELETE if the account has no password. The page is also at /delete-account.