If you choose to install Windows 10 on the disk where an existing installation already exists, the installer will rename the old Window's folder to Windows.old in the root of your disk. This folder will contain a full backup of the previous Window 8 or Window 7 installation. The folder also includes the boot manager and your installed applications.
The feature this is very convenient if you plan to uninstall the currently installed one version of Windows and return to the previous installed version. It may also be useful if you have forgotten to transfer some files or settings to the new installation.
However, if you've finished with all of this, then the Windows.old folder only captures your disk space for no reason.
Below we describe how to him delete using built-in Windows tools instead of simply deleting the folder from Explorer.
Press the two Win + R keys together and type the following command in the RUN box that will appear:
cleanmgr
Θα εμφανιστεί το cleanmgr. Κάντε δεξί κλικ πάνω του και επιλέξτε "Εκτέλεση ως διαχειριστής". Όταν ανοίξει η εφαρμογή, περιμένετε μέχρι να τελειώσει με τον υπολογισμό χώρου του δίσκου σας.
Scroll down, at the end of the list of options you will find the option to delete the previous Window installation. Select it and click OK.
You're done, of course you can also delete the C:\Windows.old folder manually, but Disk Cleanup will automatically resolve the permissions accesss of NTFS and will delete all files that are not accessible from your account.
In the case of a manual deletion, you will need to resolve these permissions access, otherwise you won't be able to delete all the files in the C:\Windows.old folder.
