Rollback from forced upgrade to useless DC.

My acrobat reader was just upgraded from an unknown version to the new DC. When I load an engineering specification file, like Maxim's ds18b20_pre1.pdf from my disk it just displays blank pages. I also displays an annoying right panel which seems to want me to stor all my files on your server and pay a monthly fee. I don't want this program! How do I rollback to the previous version! Paul_L