One of my computers is a HP stream, which has a low amount of total storage space. I recently have been trying to downgrade from Windows 10 to Windows 8.1. During the 8.1 setup process while using a usb flash drive, it says that I need at least 4.7 GB of free space on drive C to finish it. I used disk cleanup and deleted some other things manually, but I still don't have enough free space to continue with it. Any suggestions?