Being a computer newbie I had no idea how to do this whilst keeping all my files so instead (as I had a spare licence of windows 10) decided to install another version of windows on to the SSD and boot from there. This seemed to work although I 'lost' (couldn't access?) all of the files I had on the previous hard drive (RIP GTA 5).
I have been using this computer for about 2 months when I noticed the computer could not install updates. I tried running the windows update troubleshooter - it found no issues. I tried running the system file checker on the command prompt (sfc / scannow), this found some corrupted files which it then fixed but the computer will still not update. Finally I downloaded CC Cleaner and did a registry clean but still not luck with updating.
I think the issue might be to do with having the two operating systems on the same PC - what's my best bet to solve this? Delete my old OS perhaps? Does anyone know of an idiot-proof program that can do this?