simple-fs-server/routes/api/logout.ts

import { Handlers } from "$fresh/server.ts";
import { deleteCookie } from "http/cookie.ts";
import { Status } from "http/http_status.ts";

export const handler: Handlers = {
  GET(req) {
    const url = new URL(req.url);
    const headers = new Headers(req.headers);
    deleteCookie(headers, "auth", { path: "/", domain: url.hostname });

    headers.set("location", "/");
    return new Response(null, {
      status: Status.Found,
      headers,
    });
  },
};