After win8 installation, how to delete the reserved window.old folder and file, release the hard disk

and refer to Win7: By clicking the "Start" button, open "Disk Cleanup". In the search box, type disk cleanup, and then click “Disk Cleanup” in the results list. If you are prompted to select a drive, click the drive where Windows is installed and click “OK”. On the "Disk Cleanup" tab of the "Disk Cleanup" tab, click “Clean System Files”. If the system prompts you to select a drive again, click the drive where Windows is installed, then click “OK”. Check the “Previous Windows Install> checkbox, and any other checkboxes corresponding to the file you want to delete, then click “OK”. In the message that appears, click “Delete Files”.