diff --git a/2-ui/5-loading/02-script-async-defer/window-onbeforeunload.view/index.html b/2-ui/5-loading/02-script-async-defer/window-onbeforeunload.view/index.html
deleted file mode 100644
index eacfda1f7..000000000
--- a/2-ui/5-loading/02-script-async-defer/window-onbeforeunload.view/index.html
+++ /dev/null
@@ -1,19 +0,0 @@
-<!DOCTYPE html>
-<html>
-<head>
-  <meta charset="utf-8">
-</head>
-<body>
-  <script>
-    function setHandler() {
-      window.onbeforeunload = function() {
-        return "There are unsaved changes. Leave now?";
-      };
-    }
-  </script>
-
-  <button onclick="setHandler()">Set window.onbeforeunload</button>
-
-  <a href="http://example.com">Leave for EXAMPLE.COM</a>
-</body>
-</html>
