how to remove Nokia 7210 memory card lock

You can solve your problem by following steps as :

1.     Go to file manager on your Nokia 7210.
2.     Go to the "Settings" option.
3.     Select system folders present there.
4.     In the "System" folder there's a file called "MMCSTORE".
5.     Send that to your PC using IR/Bluetooth.
6.     Then open it in notepad.
7.     The password you need for your memory card is in that file which you can replace.