IPhone 4S, iOS 7 to iOS 6 downgrade?

Any possible way to downgrade iOS 7 to iOS 6 on iPhone 4S without having to jailbreak? Please help

Thank you for your time.

Added (1). "Factory default" via iTunes maybe?

Usually if you download the IPSW file (apple firmware file) from Felix burns "google it" and when you shift click on restore I think and you can select the firmware you downloaded

I don't think you can downgrade.