Update: I have found the solution to my own problem above.

I hid all the menu items from guests via the Studio->Navigation->System->Site menu area.

Then I added the following css code to Designer injection to prevent the hamburger menu and navigation menu items to display to guests when you zoom in the page or when you resize the browser window or when you view the page on the phone (mobile view):

<style>
.bx-user-unauthorized .bx-ti-hamburger {
display: none;
 }
</style>