Then again, users who have installed the service pack without complications do not necessarily need those backup files that allow them to uninstall the service pack anymore. These users can free up disk space on the Windows partition by deleting the backup files.
I recommend to test the operating system with service pack at least for a few days before you make the decision to delete the backups. Impatient users may create an image of their system partition instead that they can use to restore the system if the need arises to uninstall the service pack after the backup data has been removed from the system.
How much disk space are we talking about? I just made the test on a Windows 7 Professional 64-bit system. The free space increased from 18.9 Gigabytes before the cleanup to 22.2 Gigabytes after. That’s more than 3 Gigabytes of space. It is likely that 32-bit users will be able to free up less space than that due to the nature of their operating system. Still, they will free up Gigabytes as well.
Removing Windows 7 Service Pack 1 Backup FilesThe easiest way to remove the backup files of the Windows 7 Service Pack 1 installation is the following. Open an elevated command prompt. You do that with a click on the start orb, the selection of All Programs > Accessories, a right-click on Command Prompt and the selection of Run as Administrator.
Use the following command to free up disk space after the service pack installation:
dism /online /cleanup-image /spsuperseded
The process takes a few minutes to complete, it ends with the sentences “Service Pack Cleanup operation completed. The operation completed successfully”.
Please remember that you cannot uninstall the service pack after you have cleaned up the disk space. Please let me know how much disk space you freed up with the command. Source: http://www.ghacks.net