My guess is it's not illegal, but you may get some trouble from ICBC. If you tell them, your rates may go up. If you don't tell them, and you get in an accident where your passenger is injured and ICBC decides that things would not have been as bad had there been an airbag in place, I can see them making a fuss. I'm guessing at all this, but I wouldn't put it past ICBC.
On a side note, I would only remove airbags on a track car. Of course I'd also remove bumper beams, interior panels, AC, stereo, rear & passenger seats, and all other bits of "safety equipment" I could find short of the drivers seatbelt.