During most upgrades Windows sets aside a backup of the previous installation in folder called Windows.old. It does this in case you need to recover data afterwards or in case the operating system needs to rollback the installation.
However, after the installation completes successfully, the user isn’t notify of the leftover folder. And this folder takes a lot of valuable hard drive space, especially if you are using a solid state drive, which still features far less capacity than the rotating platters drivers.
Windows.old sits silently at the root of C:\ and contains the operating system files, the Users folder (with your personal documents), Programs Files and Program Files (x86) and other data. And if after upgrading to Windows 8, you don’t need its content, it is safe to delete it and reclaim some precious disk space, which depending on the version of Windows and applications you installed, it could probably be several gigabytes (12-20GB or even more).
Before removing any data to recover some additional hard drive space, make absolutely sure that you don’t need any of your old documents, music, videos, pictures. (This previous guide can help you to recover any file, if needed).
Also with the Windows.old is possible to recover or rollback to, for example, Windows 7, something that isn’t documented, but it is certainly one thing you can do. If this is something you need to do, don’t delete the “Windows dot old” folder and follow these instructions.
Once you are positive, you don’t need the Windows.old and you’re ready to free-up some space in your hard drive follow the steps below:
1 Although, you might think that hitting the Delete button will do the trick, it is not the case. You’ll get a Folder Access Denied alert.
To properly delete the .old folder you’ll have to use the Windows Disk Cleanup. Finding the tool is easy, just go to Computer, right-click the C:\ drive, select Properties, and then click Disk Cleanup.
2 You’ll notice that after Disk Cleanup runs the Windows.old folder isn’t included. This is because you need to run the Clean up system files option. Click the button, the tool will restart, but this time it will included the previous installation folder.
3 Select and check Previous Windows installation and click OK. Disk Cleanup will take over and properly get rid of the folder.