Its obvious that you don't want this letter to be up from your tone and comments.
Before we go into legal hashmash (which is off topic here), lets explore some other options to get what you want (the letter removed).
Your first step would be to contact the company that put the letter up, if you can see who did it. Outline your concerns to them and politely ask them to take it down. If they don't react, or react negatively, you can go on to the second step.
The second step would be to contact the website, with the same polite request to take it down. If the website doesn't react or also reacts negatively, you can contact a lawyer and get legal advice. I strongly advise you that if you want to cite any laws (like mentioning that this is illegal in your correspondence with either website or company) that you get an actual lawyer to look into it first. Try the polite approach first, it very often works with minimal hassle.