In order to resign as president you need to send a letter of resignation. You may also be a director and if you want to completely disassociate yourself from the corporation you will also need to resign as a director if you are one. If you are a shareholder, there may be a shareholders agreement that establishes the protocols for the transfer of shares. It sounds as if you should speak to a business attorney in your area to review the corporate documents and advise you in the matter.