1988 Buick Riviera reset the computer

I want to reset some store codes on the computer display, I already disconnected the battery for a few minutes and did not work ,, so I removed the computer, pulled it out complete and even removed a couple of chips and put them back but the stored codes still show on the computer display, this is a t-type buick with the small computer display where you con touch the screen and you can navigate the screen display.