Yes, lawsuits probably would be the main way to deal with this unfortunately to either unwind the original equity grant or have him removed. There may be some loopholes in the bylaws and corporate law in the state of incorporation that could provide for removal of a CEO. Sometime a minority shareholder does have some rights, but without majority vote, it is pretty tough to force anything. What Mr. Byrnes said is correct though, as CEO and, in some cases, as majority shareholder, he has certain duties to the company and other shareholders, but that would be timely and expensive.
I am not saying that the IP developed is not the company's, but there is also an argument to leave with the Intellectual Property and start a new company if the other person is completely gone. I don't know the specifics of your IP or what actions you have taken to protect it or put it in the company's name. You are in a tough spot, but trying to work out a resolution with them and if not, talk to an intellectual property lawyer about what rights you have over your developments and see if you could try to take it with you to start a new company and bring those VC investors over.