From the moment you enter a Google account, the phone will automatically enable data connection and it will send a PIN to that email account; but in case it can't activate data connection to send the recovery PIN you will need to factory-reset your phone because there isn't another way to remove the lock screen.
Turn off the phone then press Volume Up + Volume Down + Home button + Power Button until the service menu appears. From that list select Wipe data/Factory Reset and the phone will reboot. When the process completes, the phone will be unlocked, but the applications installed will be deleted and restored to defaults.