Alright unlocked to say this
I successfully did it yay.
Steps on how I did it.
>> buy/get whatever version of windows I want (This gives you an .iso of windows)
>> Put it on my usb via rufus (Windows didn't work)
>> Restarted computer, hit f12 as it was starting up, went into boot section and changed the boot order to USB then HDD.
>> Put in USB, restarted computer and went through the install, chose custom install to format my original C: drive, installed windows 8.1
>> Finished, didn't need to change boot order back as if I needed to restart again, I wouldn't need to change it back.