It may happen to you that you have found an Windows.old folder on your system drive (mostly it’s C drive) and discovered that it is the main reason your system drive is hugely filled up for no reason. If you are unsure about the folder, you might get confused if you should delete the folder or keep it just because it could be a necessary folder used by your current Operating System. Actually the reason behind this folder is, you (or your admin) recently installed Windows on this PC using custom method and didn’t format the drive before proceeding.

Multiple Windows.old Folders in C Drive

What is Windows.old Folder

Starting from Windows Vista, when you install Windows in custom installation method and don’t format the drive (the drive on which your previous Windows is installed), the new Windows will not remove the old Windows and user files – instead it will put the whole old Windows in a folder naming Windows.old. At the process of Windows installation, you cannot prevent your current windows from doing this unless you format the installation drive. This feature is continued with Windows 7, 8 and 10.

Why Previous Windows is Kept in Windows.old folder

You might wonder that why your old Windows should be kept as you are already leaving it for the new. The answer is very simple. You could forget to backup something that you left on your previous windows. Or there’s a big chance that you left necessary files or documents on user folders like Desktop, Downloads, Documents, etc. of that earlier Windows. This kind of scenarios has already been happened to Windows XP users and Microsoft felt the necessity to not to remove the previous Windows installation – so that you can use Windows.old folder to recover previous files.

Note: You can have more than one Windows.old folder if you don’t cleanup the previous one and make more new installation in similar way. The folders are named hierarchically such as Windows.old, Windows.old.000, Windows.old.001 and so.

What Windows.old Folder Contains

  1. Windows: All Folders and Files from previous Windows Installation.
  2. Program Files: Programs you installed on that Windows.
  3. Documents and Settings: This includes both user and program created files and settings.

Why Windows.old Folder Cannot be Deleted Manually

You cannot delete the Windows.old folder or its files completely using normal deletion methods. Because it contains system files. Whenever you try to delete files inside it normally, at any time you end up getting the messages like “You require permission from administrators to make changes to this file” or “Access Denied” though you are the admin on your system. You either have to take further permissions using Windows Command Prompt or use the following easier procedure.

Before Deleting

Note that once you delete Windows.old folder using the procedure mentioned below, you cannot undo it. So before deleting, it’s time to make sure you didn’t leave any necessary file on that earlier Windows. If you are confused, I suggest to check the desktop and downloads folders inside that old folder. Shortly you can do it by pressing Win+R, writing %systemdrive%\Windows.old in input, and checking possible folders for important files.

The main reason you should remove Windows.old folder is, you no more need it and it is eating up huge potential space on your system partition.

How to Completely Delete Windows.old Folder

  1. Right-click on the System drive (the drive where Windows.old folder(s) located). Choose Properties from context menu.
    Bring Properties form right-click
  2. Click Disk Clean-up button from drive properties window.
    Choose disk clean-up
  3. Right after, Disk Clean-up will check for cleanable files and calculate the size. Wait for next screen.
  4. Again click on Clean-up system files button from the cleaner window.
    Click on Clean-up system files
  5. Right now it will check for junk system files including Previous Windows Installation(s).
  6. As soon as the scan is finished, you will find it offering you to choose Previous Windows installation Files too. Select it and review other selection options. Then click OK.
    Mark Previous Windows Installations
  7. Click Delete Files when it asks.
    Choose Delete Files
  8. Right after, it will start to clean up junk files you choose to remove including the old Windows Installation folder Windows.old and files inside it. That’s it.

Note: You might still find the folder remaining there. If so, right-click on the folder and choose Properties and check the total size. If the size is as small as a barb fish, just don’t bother it. All files inside it are actually deleted.

Closing Words

It’s huge disgusting when you fail to completely delete the junk Windows.old folder. Using the right way makes it a lot easier.

Via TheWindowsClub.


Jaber is a Programmer and Tech Enthusiast Geek from Dhaka, Bangladesh. He is the founder and Chief-Editor of TechGainer. While he is away from his keyboard, either he's fishing or messing with wildlife. In case, you can contact him at rijans[at]techgainer[dot]com.