If you’ve ever run the Microsoft Windows Disk Cleanup utility, you probably discovered that your temporary files occupy a significant amount of space. You might select the Temporary Files check box in order to allow the Disk Cleanup utility to delete the files in the Temp folder, but the Disk Cleanup utility will not remove all the files. The reason for this oddity is that the configuration for the Disk Cleanup utility does not allow deletion of files accessed in the last seven days.By altering the LastAccess value in the registry, you can configure the Disk Cleanup utility to delete all the files in the Temp folder regardless of the last accessed date.

Check it: Force Disk Cleanup Utility To Delete All Temporary Files