add sessionDestroy func

example/test.ts

@@ -82,7 +82,7 @@ httpServer.get("/site", (_req, rep) => {
 httpServer.delete("/session", (req, _rep) => {
   const username = req.session.user as string ?? "";
   if (username.length > 0) {
-    delete req.session.user;
+    req.sessionDestroy();
     return {
       code: 200,
       message: "Logged out!",

mod.ts

@@ -448,6 +448,10 @@ export class RouteRequest {
     }
   }
 
+  sessionDestroy(): void {
+    this.session = {};
+  }
+
   header(name: string): unknown {
     const matchingHeader = Array.from(this.headers.keys()).find((headerName) =>
       headerName === name