I seem to remember being able to remove a mask from an image in Acrobat but I can't remember where the command is. Does anyone know where this is?
I'm still in Acrobat 8, but this seems to work. With your PDF open to the page you want, select the Touch-up Object tool. Right-click on the page and select Edit Page. That page should then open up in Illustrator, where you can edit/delete the mask. Save the changes in Illustrator, and it should update in Acrobat. I don't know what all could go wrong in this process, but it seems to work.
That got the job done. Thanks.