Deleting a lessons page is a two-part process. First, you must remove the Lessons page from the Tool Menu or page link, and then you can delete it from the site.
Go to Lessons.
If you titled your page something other than Lessons, select the title of the page as it appears in your Tool Menu.
Click More Tools, then Remove Page.
From the More Tools drop-down menu, select Remove Page.
Click Remove.
This removes the page from the Tool Menu but does not remove it from the site.
Next, go to the Index of Pages.
Select page/s, then click Delete selected pages.
You will see the list of pages with the unused pages listed at the bottom. Only items that are not linked from any other location can be permanently removed from the site.
Click Delete selected pages to completely delete the selected page/s from the site.