While this is clearly not the official ESTA website and their business model may be questionable, I believe that this is a legitimate business website and I see no reason to worry that your personal data may be used illegally. If you're concerned that you've given them your consent to process your personal data in a way you wouldn't like, you can write to the e-mail address listed on their privacy policy page and revoke your consent:
Revocation of your consent to data processing
Some data processing procedures are only possible with your express consent. A revocation of your already given consent is possible at any time. An informal notification by e-mail is sufficient for the revocation. The legality of the data processing up to the revocation remains unaffected by the revocation.