Delete a page from a PDF: Choose View > Thumbnails or View > Contact Sheet, select the page or pages to delete, then press the Delete key on your keyboard (or choose Edit > Delete).
When you delete a page from a PDF, all the annotations on the page are removed as well.
Move pages in a PDF: Choose View > Thumbnails or View > Contact Sheet, then drag the pages to their new location.
Move a page from one PDF to another: In each PDF, choose View > Thumbnails or View > Contact Sheet, then drag thumbnail images from one PDF to the other.
You can also create a new PDF by dragging thumbnails from a PDF sidebar to the desktop.