Select "Delete Page" from +/- menu in book builder. See the image below. This deletes the current page (page number highlighted in blue), and the book pages shift left by one position, resulting in a blank page at the end of the book. Note that the first time you delete a page it will not reduce the number of pages. This is because you can only delete a sheet (two pages) from a physical book. The subsequent time you delete a page, it will reduce the number of pages in the book by two. This is because when you delete a single page the number of sheets in the page remains the same but if you delete two pages in a row, then a single sheet is removed. Also keep in mind that our photo books require a minimum of 20 pages. So you cannot delete pages if the book has 20 pages.