If desired, you can customize the URL of a page or landing page.
When creating or editing a page using the Page Content and Options, uncheck "Automatically Generate a URL Alias." You'll find that under 'Navigation'.
After that you can enter an alias yourself and save the page.
However, it is important to understand that this url will not be used by the menu.
The URLs of the menu follow the menu structure.
You can use the custom url for email campaigns and the like.