You can't. Below is an extract from a reply provided by Steve R a couple of
days ago to the same question.
You can move some of the content from the PDF into a new PPT presentation as
text or images, but as one very expert PDF user put it, going from the PDF
back to the source document is like trying to convert beef stew back to raw
carrots, potatoes and meat.
More on what you *can* do is here:
Import PDF content into PowerPoint
http://www.rdpslides.com/pptfaq/FAQ00054.htm
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Michael Koerner [MS PPT MVP]
I have a caller who has a pdf file that used to be a powerpoint, and he
wants to know if there is a utility that will covert it back into
powerpoint, easily.
christinaworks