Computer authorized to old (defunct email address), updated Adobe ID. Digital Editions (reinstalled twice) won't decrypt and add downloaded PDF books

iMac Intel running OS 10.6.8   I downloaded purchased books from Google Play/Books in EPUB and PDF.  They are encrypted (.pdf.acsm).  Adobe Digital Editions reader will not add them to my library because, I suspect, my computer is authorized with an Adobe ID that uses a now defunct email address.  I have updated my ID on the Adobe web site, redownloaded and reinstalled Adobe Digital Editions but my computer remains authorized to the old Adobe ID.  How do I decrypt these purchased books and read them in Adobe Digital Editions on my computer?