So, how do you do it? I had to buy 2016 from CDW. They assured me it is able to be downgraded, but could not tell me how. Now I need to do it. I tried installing 2013 and using the 2016 keys, but it would not work. There doesn't seem to be a good source of info on this. I did find some that referred to Office365, but not the retail/standard software option.