In October of 2013, Microsoft released an update to the Disk Cleanup utility for Windows 7. The KB article concerning this update can be viewed at:
Once installed, launch the Disk Cleanup utility as normal. Select your default partition.
Click on the “Clean up system files” button if the user account in question does not have local administrative authority as in this example.
When the application reloads, the list of items should include a new entry named “Windows Update Cleanup.” In this example, this entry was over 3 GB in size.
During the next reboot, the boot screen may display a notification stating that some maintenance tasks are being performed.