reprogramming ignition key code

[dagoninfinite]

hello, everyone. I have a security concern: some other person may have an ignition key to my Ford Explorer 2002 (made in 2001). Is there a way I could reprogram the keys code to disable any ignition keys except the ones I have?

 

[formulamojo]

It is my understanding only the dealer can do this. And for my mountaineer when I wanted remote start the key was 85 and the program was 20. I decided I could bear the cold to go start the truck in the winter.