Revert "Add initial authentication system"

This reverts commit 1871ea9eb7.

src/components/Admin.vue

@@ -1,33 +0,0 @@
-<template>
-  <div class="hello">
-    <h1>Welcome to administrator page</h1>
-    <h2>{{ msg }}</h2>
-  </div>
-</template>
-
-<script>
-export default {
-  data() {
-    return {
-      msg: "The superheros",
-    };
-  },
-};
-</script>
-<style scoped>
-h1,
-h2 {
-  font-weight: normal;
-}
-ul {
-  list-style-type: none;
-  padding: 0;
-}
-li {
-  display: inline-block;
-  margin: 0 10px;
-}
-a {
-  color: #42b983;
-}
-</style>