We cover editing your sites Menus through the Dashboard. Appearance -> Menus (or from the Admin menu bar Blog Title -> Menus).
But you can now also edit the menus in the customiser:
- Click Customize in the Admin bar when logged in.
- In the customizer click Menus
- Choose your menu and edit.
Here is a quick gif showing 2 ways to reorder your menu:
Depending on your menu and how you like to work this may suit you better that the Dashboard method. If you are using the customizer you can see a preview of the menus as you work