Are you on a Z visa or any other visa in China? Did Hamspon provide you with the documents to apply for a Z visa in your home country and did they sponsor your residence permit or the like?

I highly doubt that they ever did. If that really is the case, you do not have to worry: If you decide not to work for them - ans I would urgently advise you not to do that! - you can throw their "contract" away without fearing anything. They would employ you illegally, and they might not be pleased to hear from you that you don't work or them. But they can't do anything against you as otherwise they would have to admit to employ foreigners illegally. And the Chinese authorities concerned like immigration would not find that particularly funny.

I suggest you look somewhere else. And good luck!