Of course only use this if you are the original owner.
If you want to just restore your iPhone with iTunes then turn off the iPhone and hold the home button while you connect it to your computer. Connect to iTunes will show up and just do a clean restore for your iPhone.
Slide to unlock>emergency call> dial 112>press the power button twice before it connects and end the call. This works on ios 6 I believe. This is how I activated my iphone and have bypassed a password before using st method.
Yes that's the only downside. While its unlocked back it up then restore it and when it says a pass code was set and gives you option to set another just say no. That's another way to do it.