If you installed the new Windows 10 Anniversary Update version over a previous one version of Windows, you would notice that your free disk space has decreased significantly.
When upgrading from a previous version of Windows, Windows 10 saves many files from the previous version during the upgrade, so the tough it fills you with files you may never need again, especially if your upgrade was successful.
Η installation it saves these files, just in case something goes wrong with your OS upgrade. If something goes wrong you can safely roll back to the previous version of Windows.
But if everything works perfectly, there is no reason to keep garbage on your computer.
Below we will see how you can free up space after upgrading your operating system (Winaero):
Press them together two Win+R keys to open the Run dialog.
Type the command and press Enter:
cleanmgr
Select the drive that is installed in your operating system (usually in C) and press OK.
Make it click on the Clean up button to activate the Disk Cleanup tool.
Find and select the files of your previous Windows installation (s).
Click OK and you're ready.