If you haven’t formatted the partition and installed Windows 8 over it with custom install option instead of Upgrade or after Windows 8 Refresh, then the files in previous version of Windows will be stored in Windows.old folder. They do occupy large hard drive space, after using Windows 8 for 1 or 2 weeks if you’re sure you won’t require those files in future, then you can safely remove this folder and reclaim disk space by running built-in Disk Cleanup tool in Windows 8, here is how to do that.

Removing Windows.Old Folder in Windows  8

1. Use Win+R command to open run box and use Cleanmgr command.

2. Select Windows 8 installed drive and click Ok,

3. Disk Cleanup tool scans the drive and shows shows lists of unnecessary files found, click Cleanup system files

clean up system files How to remove Windows.old Folder in Windows 8

Now Disc Cleanup again asks to select the drive, select Windows 8 installed drive, click  ‘OK’, this time, the tool scans for previous Windows installation files and displays them if found.

4. Select “Previous Windows Installation” and click ‘OK’ to let Windows delete them safely.

Select Previous Windows installations How to remove Windows.old Folder in Windows 8

Update October 23, 2014: By using Disk Cleanup too, you can able to delete Windows.old folder in Windows 10 TP also.

Update October 25,2013: You can use above same instructions to remove Windows.old folder in Windows 8.1 also, CCleaner also cleans that folder.