You have not indicated if you and your old business partner are the only shareholders of this corporation or if there is a shareholder agreement that contains restrictions on, or procedures for, transfer.

Assuming that there are only the two of you, and there is no shareholder’s agreement, you would need to have a meeting of the shareholders to approve the transfer and a written assignment of the shares that indicates the consideration (what you are paying in cash or kind) for the shares. Some states permit a written “consent” signed by the shareholders in lieu of an actual meeting. Finally, you need to retrieve your partner’s share certificate and mark it cancelled and issue a new certificate for the shares in your name. All of this should be properly documented in the corporate records. You should consult an attorney
familiar with these transactions to prepare the proper documentation.