How to change a president on C-type Corporation?

My partner and I have a C-type coporation that we opened a couple of months ago. The president of corporation is him and I hold 50% of shares. My partner want out because he is starting the family, therefore I need to become a president and 100% owner. How do I do that? Would it be enough for him to sign a share with his 50% transfer to me? Or do I need to fill out a special form or a letter signed by both parties?