next.js/examples/cms-umbraco/pages/api/exit-preview.ts

import { NextApiResponse } from "next";

export default async function exit(_, res: NextApiResponse) {
  // Exit Draft Mode by removing the cookie
  res.setDraftMode({ enable: false });

  // Redirect the user back to the index page.
  res.writeHead(307, { Location: "/" });
  res.end();
}