Before an airbag light can be shut off or reset, the airbag ECU must be cleared, according to CarsDirect.com. The website recommends removing the airbag ECU and taking it to a car mechanic who can run a diagnostic on it and either repair or replace it. This type of work should only be handled by a professional, as an improperly repaired airbag may not deploy properly, which is extremely dangerous.
If it is determined with certainty that there is no malfunction within the airbag system, Airbagsolutions.com notes that in some vehicles, a cycle of the ignition or toggle of the door jamb may help to trip the necessary reset switch for the airbag. The website also explains that for some cars a special scanner tool is necessary to reset the airbag light. There are many kinds of scanner tools available, and Airbagsolutions.com has a large database of instructions on how to use them to scan thousands of different vehicles. Special software is required to read and reset the airbag system. It's important to refer to the scanner manufacturer's service manual to understand the correct procedures and equipment necessary for troubleshooting the airbag problem. Any attempt to reset the airbag light should be followed up by a visit to a professional mechanic.