how to nintendo dsi xl restore?

[DarrenCinco]

i just bought this dsi xl off of craigslist it has profiles and stuff already on it. im trying to restore it back to factory settings but i cant find how ive gone through settings already. also this xl has a parental password so far i havent had a need for the password but i want to change it or get rid of it. i tried contacting the person i got it from but they wont reply all of a sudden (so im sure it is stolen or something). can anyone please help me out?