Once triggered, the light won't go out without an airbag reset, sadly disconnecting battery alone won't do it
It's quite probably one of the connectors under the seat - my passenger side seems prone to it, and it doesn't
help that I keep offering lifts to short people one day and great long, lanky sods who insist of speeding the seat all the way back the next day
VagCom or a friendly dealer will tell you which sensor triggered it - if it's a seat one, tape it up