But you do not return to Main Menu. You create another Main Menu. Now you have 2 main menus. For a while at least; since the Main Menu is not referenced (never was? - we can’t see how it’s created for the first time), it will be scooped up by the Garbage Collection in a little while.
Perhaps look into how a Widget Switcher works. Think of it as of a book where each widget is a page and the book can only show one page at a time. You can switch between the pages without having to remove / create them. And since all pages exist, you can still control with them, even though they’re not showing atm.