A: When a service pack is installed, the files that get replaced are packaged up and stored on the local machine so the service pack can be uninstalled if necessary. You can remove these files to save space, or if you're creating a base image that will be duplicated and you don't want extra space consumed. The easiest way to remove is using the DISM tool, as follows.
C:\Users\john>dism /online /cleanup-image /spsuperseded
Deployment Image Servicing and Management tool
Image Version: 6.1.7600.16385
Removing backup files created during service pack installation.
Service Pack Cleanup operation completed.
The operation completed successfully.
This process may take a while, depending on the performance of your machine.