add sessionDestroy func

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