1. Insert two pin keys or special radio removal keys into the holes on both sides of the radio.
2. Push the keys in until you hear a click.
3. Press the release button on the side of the radio.
4. Pull the radio out of the dash.
Depending on the model year of your Opel Combo Van, you may need to remove the climate control panel in order to access the radio. Some newer models have the radio integrated into the climate control panel, so it is impossible to remove without special tools.
If you are not comfortable with this process, you can always have a professional install your radio.