You can only disable the airbag for safety reasons. If you are too short, or too fat, or for some other reasons you are too close to the steering wheel while driving you can have the airbag disabled because in the event of an accident the airbag might kill you.
If you disable the airbag with no good reason and get into an accident, your insurance company might decide not to pay, and the cops might decide to give you a ticket just has if you were not wearing your seatbelt.
Funny thing is that a recent study of high speed accidents showed that the survial rate is 65% with the seatbelts and 68% with seatbelts and airbag... Seems like the airbag is a marginal improvement.
MH
On a clear disk, you can seek forever...