What is this annoying Office Upload Center?!

@ strollin, it could have something to do with having installed SkyDrive app (maybe called OneDrive now). This is a copy of a reply on a MS website to do with the Office Upload Centre disabling.

"Do you have SkyDrive desktop app installed? If so, it will have become integrated with this Upload Center. To disable SkyDrive for use with Office 2013, follow these steps:
Right-click the SkyDrive icon in the notification area, at the far right of the taskbar. (You might need to click Show hidden icons first to see the icon.) Then click Settings.
On the Settings tab, under General, deselect Use Office to sync files faster and work on files with other people at the same time, and then click OK."

I have Office 2013 Pro installed & I don't get the Office Upload Centre icon either. I do not use OneDrive & I don't have the OneDrive app installed either.

I think you may be on to something there. On this computer, I'm running Win 8.1 with a local account which does not allow me to connect directly to OneDrive. I use a 3rd party app (syncDriver for OneDrive) to sync OneDrive.