I downloaded the software that is at the equivalent level of the OS that was in my machine. I had purchased a laptop with some mild version of Win 8 and purchased the full-octane version at work (at universities we get software at a deep discount). Upgraded to the heavy duty Win8, then Win 8.1 came along and I did that upgrade. I figured out more or less how to use it, but there was a crash a while back and the Microsoft tech in India couldn't get the 64bit version to operate so loaded and ran the 32bit version. My machine was crammed full of old OS files by this time and since it is a SSD device it didn't have that much room to begin with.

I had to uninstall a few things and then I did the Win 10 upgrade. Once I determined it was working I simply cleaned the disk and used the appropriate button to remove the old OS files. While I was at it I compressed the contents of the disk, so I've cleared a lot out one way or another. If I do this on the desktop (it runs Win7, and runs very well, also the ultimate version) I won't bail on the old software in a hurry.

The upgrade and the clearing of old OS didn't take more than a couple of hours, but the compression took many hours. Overnight and into this afternoon.