Make a copy of the file first work on the copy so you don't mess up your only copy of the original.
There IS a way to extract an embedded PDF from an existing PPTX file though. The code, they just latch onto what Windows already provides and give us a way to use it. Embedding and linking objects is built into Windows the PPT devs didn't need to write The root of the problem is that both versions of PPT give us features that are inexpensive to develop because they rely on features provided by either MacOS or Windows.
