Microsoft offers free upgrade to Windows 10 for all the Windows 7 SP1 and Windows 8.1 users. On these older versions of Windows, Windows 10 is downloaded and installed through the automatic updates. You can also download an ISO image of Windows 10, burn it to a DVD and then upgrade your existing Windows 7 or Windows 8.1 system to Windows 10. In both the cases, your older Windows files are copied to a folder named Windows.old in the event you may want to downgrade to the previous versions of Windows in future. But if you do not want to downgrade and keep using the new Windows 10, then you can delete all the previous Windows version related files and free up multiple gigabytes of space from your disk.
You cannot just delete the Windows.old folder as it requires special privileges (not even a system administrator can delete this folder completely). For removing the files related to the older Windows installations, you have to use the Disk Cleanup utility. Here is how:
- Press the Windows logo key and type disk cleanup in the search box. Click on Free up disk space by deleting unnecessary files in the search results.
- Choose the disk drive on which Windows is installed. Usually it is the C: drive, but you can identify it through the Windows logo disk drive icon. Click OK to continue.
- Click on the Clean up system files button when the Disk Cleanup windows shows up.
- Disk Cleanup will be closed and launched again with administrator privileges. Select Previous Windows installation(s) from the list of files to delete. You may select other items from the list too, but be careful what you want to delete. Click OK to proceed.
- You will be asked if you really want to permanently delete the files from the selected categories. After you click on the Delete Files button, it will delete the Windows.old folder from your system.
On a typical Windows 10 system that was upgraded from Windows 7, it frees up 5-6 gigabytes of disk space when you clean the previous Windows installation files. But at the same time, it also makes it impossible to downgrade back to the older versions of Windows through the backup of the installation files. However, you an always downgrade using a Windows 7 SP1 or Windows 8.1 installation disk.