New York  |  Business Law

I own a company that is in my name. I took on two partners (one is my wife who is a chinese citizen with no ss #). The other is an American. We all own 1/3. The only thing I have stating that the other two are partners is a single piece of signed paper with a few sentences saying that they are both 1/3 owners with me, nothing more. My wife and I want to buy out the other partner. He will probably not want to leave. What can I do?