I'm having the same problem. Running Win 10 and Office 2016.
iCloud won't run, won't repair or uninstall through "Programs and Features".
So all my contacts that I use for business are unavailable on my desktop b/c they were removed when I signed out of iCloud.
This is a "fatal error" as I can't work without access to my contacts being in Outlook.
From the other posts, looks like this has been going on for some time. I was a little afraid to upgrade to Win 10 and Office 2016, but kept getting bombarded with reminders so I finally did it. Now I'm regretting it very much!
Heeeeeeelp!