On the C drive you have $Windows.~BT folder which contains the Windows 10 Installer files and Windows.old folder which have your old OS files. Even machine which was upgraded from a completely clean Windows 7 install and wasn’t even updated still losing about 14.5 GB of your disk space. I don’t want to wait until Windows clear it up by itself, so let’s try to gain our GB back.
To free up your disc space and clean up old OS files you need to use Disk Clean-Up.
Go to Computer => right click the C drive => Properties => Disk Clean-Up. Run the application.
Now you will get files list that you can delete.
Select «Clean up system files» button.
Disk Clean-Up now is going to look for some other things he can remove, including system files.
Now you can see Previous Windows installation and Temporary windows installation files in the list.
Select them both and press OK. Now go through the Clean-up process and remove them.
That`s all. I hope this tutorial was useful for you to free up 14 GB disk space!