Aha! So there is. So it's not bad implementation, just bad UI design.

So the trick is:

- Change your email address to something like kjghoyvgljhbvljhvkljhbv@mailinator.com.

- If you get a confirmation message to your old address, delete it.

- Change your password to jkhvouyflkjbv7897t^%REjhvljyyf.

- Go to the mailinator address to confirm the change.

- Clear your browser history.

Then you're free of HN forever! ... Or until you make a new account.