Every guide I can find says the master code is 7444, one says you have to press Select at the same time as the last 4.
Change or delete parental lock
Press Start when prompted to enter the code. Once you get to where you enter the numbers, press Start and you will be asked if you want to delete it. You can also enter another code instead of deleting it. The master code is 7444. Enter it, and at the last "4", press Select at the same time. Do this again, and you will eventually get the option to delete the lock. Enter 7444 again to delete the code.