Unwanted program

Hi. So I am hoping i am not the only one who has ever wondered this, but my computer is like a room that I like to keep clean. You might give it a tidy and a vacuum every so often and throw out some old junk but look under the bed or behind the wardrobe ,and alas, there is hiding nasty things...

So this is what I'm hoping to accomplish. I want to download a free copy of Windows 8.1 provided by my college onto a hard drive on my laptop. Then I hope to move that download onto a ssd and then use that ssd in my new build. Is this possible? When I download Windows is it tethered to my...