On the Page Sorter, each page thumbnail offers a menu through which you can access a number of page formatting options.  You can right-click on the thumbnail, or just click on the down-arrow in the upper right corner of the thumbnail to access this menu of options.  Using this menu you ca adjust page size and orientation, background colour (or image i background), set grids and switch them on or off, clear pages of any content, and delete pages altogether from the Workbook.