Page 52 of the Owner's Manual gives the answer to this: 1. Switch off the…
Reset service light Skoda Octavia 2, 2004, 2005, 2006, 2007
1. Switch off the ignition and press the reset knob of the trip counter below the speedometer and hold.
2. Switch on the ignition and release the reset button, one of the service events appear in the display.
3. It is possible to switch between the the readouts of the service events by briefly pressing the reset button.
4. When the particular service event is displayed, turn the button for setting the digital clock to the right, service appears in the display.
5. Switch off the ignition. Only now is the service event reset.