When you have a single subpage in your navigation, you can easily move the page back to the main level at anytime.
Here's how:
In the Website Builder, click the Manage Pages button, which is located in the main toolbar, next to the Site Builder
menu.
The Page Manager opens and the pages associated with your selected design template appear:
Select the subpage.
Move the page to the left, back under the main page.
Notice that the check mark no longer appears at the main page level.
The subpage is moved back to the main level.