Cannot CROP PDF pages


I’ve just purchased PDF architect 6 including the editor.
I thought that the editor would enable me to be able to
CROP the horizontal or vertical areas of a document.

For example, sometimes when you save a PowerPoint
file to PDF, it leaves a white space at the top and bottom
of the PDF. I want to be able to crop the top and bottom of
the PDF. Alas, it doesn’t look like I can.

Can anyone give me assistance as to how I can crop
the entire PDF document in Architect 6.

Paul, Australia