SP1 file ?

I was reading a Windows article about how to uninstall SP1 ( no, I have no intention to uninstall ).
I came across this pharagraph ......
If you've used Disk Cleanup since installing SP1, the backup files needed to uninstall the service pack might have been deleted from your computer. To remove the service pack, you'll need to reinstall Windows 7. For installation information, see Installing and reinstalling Windows 7.

Question :
Which backup file is that ?
Where do I find it in disk cleanup list.
I want to uncheck it so I still have the option to uninstall if I want to.

Thank you.

richc46 said:

Go to disc clean up.
Before it cleans the files it will show you which files will be deleted. It also allows you to check clean up system files.
then clean up system file
You will have the option to tick or untick, SP1 install file
Windows 7 SP1 Disk Cleanup Tool

It is called Service Pack backup file

Thank you.

Edit : It won't let me give you the rep point.
Wonder Why ???
You were not the last one I gave rep to. So, why can't I give you rep points ?