Go to /applicant/forgot-password. Enter the e-mail on your account, upload the same resume file you applied with — the exact file is what proves it's you — and choose a new password (at least 8 characters). Every other session on your account is signed out.
Don't have that file any more? Use the recovery questions instead (/applicant/forgot-password/quiz): a few multiple-choice questions about your applications. Answer them all correctly and you can set a new password; a wrong answer locks the quiz for 48 hours.
Still stuck, or can't get into the e-mail you used? Send a change request ("I can't get into my account") and a person will confirm it's you. You don't need to sign in to cancel a subscription — see /help/cancel-subscription.
Everything we hold about you is one e-mail away, with a download and switches for each consent.