refactoring: removed redundancies from Menu in Main class

src/main/java/org/example/Main.java

@@ -72,15 +72,9 @@ public class Main {
                     // View Grades from Student
                     break;
                 case 11:
-                    // View User
-                    break;
-                case 12:
                     // Delete User
                     break;
-                case 13:
-                    // View Course List
-                    break;
-                case 14:
+                case 12:
                     // Exit (includes saving data in the files)
                     exit = true;
                     System.out.println("Exiting...");