You will have to reset the phone using the Recovery Mode. This might not delete the custom data like music, pictures, documents, etc., but it will erase the call logs. Unfortunately, this is the only way.
To access the Recovery mode, turn off the phone then press Volume Down + Power/Lock button for 10 seconds. Once you are in the Recovery mode, select Wipe Data/Factory Reset and reboot the phone. This will wipe the PIN assigned to your phone.