2003 Chevy Impala

It can be done two different ways:

-turn the ignition to ACC or ON and turn the radio off
-press and hold the TUNE DISPL button on the radio for at least five seconds until SETTINGS is displayed
-press the SEEK PSCAN up or down arrow to scroll through the main menu
-press the 1 PREV or 2 NEXT button to enter the submenu. RESET will be displayed
-press the TUNE DISPL button to reset
-once the monitor has been reset, scroll until EXIT appears on the display
-press the TUNE DISPL button to exit programming.

You can also use your brake pedal:
on some models you
-turn key to ACC or ON (engine off)
-press on the brake pedal five times rapidly

on others you
-turn key to ACC or ON (engine off)
-press on the brake pedal three times within 5 seconds.

I can't remember which one (5 or 3 times) is the right one for you; but if you try you'll figure it out :)