This may not apply, as I have the 92 400e. If you look under the dash (head under airbag, looking up), you may see a hole (roughly centered) with a screw deep in it. Undo and remove that screw (very long) and slide airbag rearward. Unplug airbag (pinch out plug carefully).
I just did this same job. While you are in there, save yourself the repetition and change the passenger side vent control bulb as well. With the airbag out, reach around and unplug the bulb.
1985 300TD 4-speed 212K
1992 400E 343K
2001 E320 72K