How can l reset airbag light (to clear) on 2000 Infiniti G20?
But my air bags deployed already so no worries about explosion.

The light will reset when the problem that caused it come on is fixed. That may be a bad sensor, or something as simple as a loose connection. This is not something you want to do yourself due to the real possibility of explosion, so take it in and have it done.

On a 2000 Infinity, there are more components to the airbag system than just the airbags. You can see what each vehicle needs on this website..http://airbagsolutions.com
Once the system is repaired properly the airbag light will go off. If you decide not to fix the problem, you need to stare at the light. In some states, it is illegal to pull the bulb.

The light will reset it self when the problem is fixed

Try trhis:

Ignition Key Method:

1) Turn IGNITION on (but do not start car)
2) After the AIR BAG warning lamp lights for 7 seconds, turn IGNITION off within 1 second.
3) Wait 4 seconds
4) Turn IGNITION on (but do not start car)
5) After the AIR BAG warning lamp lights for 7 seconds, turn IGNITION off within 1 second.
6) Wait 4 seconds
7) Turn IGNITION on (but do not start car)
8) After the AIR BAG warning lamp lights for 7 seconds, turn IGNITION off within 1 second.
9) Wait 4 seconds
10) Turn IGNITION on (but do not start car)
11) Wait 3 seconds
12) Turn IGNITION off
13) Wait 2 seconds
14) START Car (the light may be blinking slower than before)
15) Wait 3 seconds
16) Turn IGNITION off
17) Wait 3 seconds
18) START Car

HOPE THIS HELPS!!!