Remove, reorder, or combine pages of a PDF in Apple Preview

Open your PDF document in Apple Preview. If the sidebar isn’t showing, choose View > Sidebar > Show Sidebar or press CMD-SHIFT-D. Make sure it’s showing thumbnails (choose View > Sidebar > Thumbnails). To delete a page, just select the thumbnail and hit delete. To reorder pages, drag them up or down in the sidebar. To add pages from another PDF, open that PDF and drag the page’s thumbnail to the sidebar of the other PDF.