How do I shrink the page size of a PDF?

How do I shrink the page size of a PDF?
How to change all scanned pages from 8.5 x 14 (legal) to 8.5 x11 (letter)

  1.  On the RIGHT Column, Go to Pages, click on crop.
  2. Double click on one of the actual pages so that the Set Page Boxes dialog box appears.
  3. Under Margin Controls set ONLY the Bottom to 3 inches.
  4. Additionally, on the Set Page Boxes dialog box in the bottom right, click on the All radio round button under Page Range