How do I reset or disable the password on my PS2 ?

I don't know what my original password/code is. Is there a default? I can't watch DVD's that are PG-13 or greater.|||is urs a slim ps2|||at settings|||its been about 3 years since i had a ps2 but it is a small reset button on the system kind of like a button on some watches where you have to use a pen or a paper clip to push it should be on the back side i think under where the power plug is