When you upgrade to Windows 10 from Windows 7 or Windows 8.1, the upgrade assistant will always backup your existing installtion either in the same drive ( C Drive) or to an external drive / partition if you choose to. This is important so when you want to rollback, you have all your files and data.
Now after a while when you are all set with Windows 10, the space occupied by the backup is not much of use. While you can always go and manually delete them, Windows 10 has better way to clean it up. As a matter of fact, this was feature was there in previous version of Windows, but if this is new, this will help.
- Open File Explorer from Task Bar, and select This PC. This will list all your drives.
- Now right click on the drive you have the backup stored. If you were never asked to select a different drive, then you need to select C drive else choose the drive you had used to save the backup.
- Now right click on the drive > Properties > Disk Cleanup. You should see the wizard looking for files thats taking up space.
- Once you get the Disk clean up wizard back, with list of files that can be cleaned. Look for a button which says “Clean Up System Files”. Click on it.
- This will rerun the wizard, and this time it will search for Previous Installation.
- When the Wizard comes back, scroll down the list to find it. Check and clean it up.
That said, make sure you are perfectly ok with the new OS, and don’t want to return back to previous installation, before cleaning up the backup files.