probably the same procedure as this for a 1998 c-class

Service display reset:

Turn the electronic key in the steering wheel lock in position 2  and
press button 0 immediately within one second twice.

Turn the electronic key in the steering wheel lock in position 0. Press
button 0 and keep it pressed. Turn the electronic key in the steering
wheel lock in position 2. Keep button 0 pressed further.

The service display with current remaining mileage or time is
indicated. After about 10 seconds an audio signal sounds and the service
display with the new  starting mileage/run time for about 10 seconds is
indicated. Release button 0.

Don't blame me if your car reacts unforeseeen ;-)

This carefully written manual instruction indicates, why Germans build
cars but no Windows platforms.

regards roland