Instructions
Place a DVD that prompts you for your password in your PS2. If you have any R rated DVDs sitting around, one of those should work just fine. It should prompt you for the password before anything else comes up.
Select "Yes" to playing the movie and select "Yes" again to temporarily suspend parental controls. This is where you would put in the password if you knew it and the DVD would play. You may try "1111" at this point, as it is often the password. If that doesn't work, continue through the next few steps.
Press the "Select" button on the screen that wants you to input the password. This should change the text on the screen from "Enter Password" to "Delete Password."
Input the numbers "7444" into the box on the screen. This is the universal password needed to delete the current password. Once you input the numbers, you should get a message that says "Deletion Complete." Press the "Select" button again and you should be prompted to enter a new password.
Enter a new password for your parental control. Make sure it is something easy that you will remember. Once you enter it in, you will be asked to confirm your new password. Enter it one more time and you should be able to watch any DVD you want.