The only way to remove the PIN is through Factory Reset. This operation will wipe the data from phone (custom settings, custom 3rd party apps, and various system files). The internal storage remains intact.
Press and Hold VOLUME UP + HOME Button + Power button until the phone turns on and then release only the Power button. While in Recovery Mode, select Wipe Data/Factory Reset and reboot the phone. Once the phone boots, primary configuration needs to be done.