How to format my iphone 4S when it is already disabled?

Connect it in iTunes and push at the same time the on/off button and the home button and keep it down until you will see on the screen a iTunes cable . After this you are in restore mode so you can restore it via iTunes .

angelia288 wrote:

My iPhone 4S is disabled due to enter too many times of wrong passcode, what should I do? How to format the whole iphone?

There are a few options. If you have Find My iPhone enabled, you may have a very fast way of resolving this. Read this article: Forgot passcode for your iPhone, iPad, or iPod touch, or your device is disabled - Apple Support