After more searching on the internet, I found a similar model and confirmed that the seat back should just pull up. So I had my in home body builder have at it. I was scared he was breaking the thing, but the back came off. One of the posts was bent and prevented easy removal.
I really like the firmness of the chair and the foot rest has been perfect for me. No back pains or leg cramps. Only thing I would want is for it to recline flatter, but I love it otherwise.