or any outside bmw workshop also can. certain faults are temp electronic glitches, which may go away after you reset the car. but since the airbag light is special (it never goes away, even if the problem does, until you reset it), you need to go somewhere, pml or outside workshop, to reset it.
however, it could also mean a real fault of the airbag. something that needs to be repaired for your safety in case of emergency. if your car is still under warrenty, send into PML. If not better retrieve the fault code and see what exactly is wrong with it: real problem, or temp glitch.