There are a few settings when it comes to the view of the PDF which then also affects the final downloaded PDF. The setting margin places a white space around the pages, so if you want to cut the pages into the correct shape and sizes then the white space can be helpful to know when the page starts and ends. The setting Page Numbers adds the number of the current page out of the entire number of pages in the publication in the margin. It also adds the name of the publication to the margin. These settings are for the entire publication.
Start by clicking Publication settings link to bring up the publications various settings. Once you see the popup, under the Basic Information tab, you will see two settings on the right titled PDF Margins and Page Numbers. PDF Margin is the setting to have or not to have white space around the pages, then toggle the button as you desire. Page Numbers is the setting for the page numbers and print title to show in the margin area, toggle this setting on or off as you wish. If you are to preview the print with both settings on, you will have a white space around the print along with the page number and title. If you toggle them off then the white space will be removed and you will be left with just the publication.