After installing Windows 10 the old version of the OS is hanging around in the background taking up useful space. When you upgrade, your old version of Windows doesn't disappear. It's still in the back of the system and goes by the name "windows.old" and takes up valuable disk space. To free up disk space following Windows 10 upgrade follow the steps below.
1- Delete the old OS;
Click on the Windows Start button and type "cleanup" to automatically search the system. A "Disk Cleanup" app should appear before you in the search criteria field. Click on it to open the application.
2- Select drive and move ahead ;
Click on it to start the utility. It will ask you to select your system drive with Windows 10 installation. By default, it’s C drive. Press “OK” and move ahead. After few minutes, you will see the Disk Cleanup option for the current Windows 10 installation. Go to “Clean up system files” Now, spot the “Clean up system files” to regain up to 20GB free space on your PC with Windows 10 upgrade. Click on the button.
3- “Temporary Windows installation files”;
Click the option with “Temporary Windows installation files”. This temporary file is the one which your PC downloaded to install Windows 10 on the system. Look at the first option i.e. “Previous Windows installation(s)”. This matters the most. This contains your previous Windows installation files. If you don’t plan to get back to the older operating system, you can tick this option and move ahead. Delete “Previous installation” files to get free space Tick this option and press “OK” to regain 20GB space on your PC with Windows 10 upgrade.