The factory settings, including the original firmware version, that shipped with your Sony PlayStation 3 are always stored in the console's main memory. If at any time you are unhappy with the results of an updated firmware version, you can uninstall it and reinstall your original version using the system's menu. Note, however, that you will lose all trophies and achievements as well as saved game data that you did not back up prior to this process.
Turn on your PlayStation 3.
Choose "System Settings."
Select "Restore PS3 System."
Press the "X" button.
Choose the "Format" option, and press "X." This will completely format your PlayStation 3's hard drive, deleting all of its contents and restoring your PS3 to its original factory settings, including uninstalling any firmware updates you've downloaded.