Problem Statement:

When opening a PDF file in Word 2016, by default if PowerPDF is installed, Word calls the Nuance Convert Assistant to convert the PDF into a Word document.  The customer requires that Word converts PDF file itself when opening a PDF, and not launch Nuance Convert Assistant.

Resolution:

Close Word 2016

Run the following command from an Elevated Command Prompt.

regsvr32.exe /u "C:\Program Files (x86)\Common Files\Microsoft Shared\TextConv\NPDFCG.cnv"

When Word is started it won't use the Nuance Convert Assistant anymore.