How do I disable the phone lock on my Samsung SGH-D500 mobile phone

[kloofnek]

I have a Samsung SGH-D500 mobile phone,had it years but as it is "unlocked",can use any network in it ,is handy when I go abroad,out of the EU zone.,to use a Sim from that country.
However,I have to put a pin in to get into the phone ...don`t want this,how can I disable it.
When I try to,it asks for password,which apparently for that phone is 00000000(eight zeros),but it says it is wrong password when I enter it..I have never changed that as have never tried to disable before.
Do I HAVE to have this phone lock pin????