add dispose to files to remove controllers when not used

Frontend/patient_manager/lib/pages/profileUserUpdate.dart

@@ -142,6 +142,15 @@ class _ProfileUserUpdateState extends State<ProfileUserUpdate> {
     }
   }
 
+  @override
+  void dispose() {
+    usernameController.dispose();
+    fnameController.dispose();
+    lnameController.dispose();
+    _focusNode.dispose();
+    super.dispose();
+  }
+
   @override
   void initState() {
     setState(() {