Dissolution of s corporation
In the state where you have the foreign entity (that's the state other than the one where the corporation was formed), you need to "surrender" that entity. That's usually done simply by filing a short form with the Secretary of State.
In the state where the corporation was actually formed, you have to find the articles of dissolution. There, the process is a little bit more complex and requires you to have a tax return that's marked as "Final" on its face. Read more about that procedure in our short article about dissolution.