Download Media Creation Tool @
http://go.microsoft.com/fwlink/?LinkId=691209
Download Windows 10 Anniversary Edition (RS1) image to 8GB USB pendrive, either x86, x64 or both.
Download KB3194798 October 2016 Cumulative update, put it on USB in update folder.
x64 :
http://download.windowsupdate.com/c/msdownload/update/software/secu/2016/10/windows10.0-kb3194798-x64_8bc6befc7b3c51f94ae70b8d1d9a249bb4b5e108.msu
x86 :
http://download.windowsupdate.com/d/msdownload/update/software/secu/2016/10/windows10.0-kb3194798-x86_30ca81056fa468110773767f5b3de65711809c90.msu
Now open command prompt as admin and stop Windows Update Service, don't worry if it's not running.
net stop wuauserv
Delete anything found within ..
C:\Windows\SoftwareDistribution\Download
C:\WUDownloadCache
Now run the setup from USB and update your windows, it can take awhile and a few automatic reboots.
When back at desktop, run the update and reboot.
When you are happy run Disk Clean-up - "Clean Up System Files" to remove old version of windows and backups, you can get massive amount of space back !