Remove two screws on the separate plastic trim piece at floor. Remove that piece. Push down firmly on centre pillar trim and release slightly away from the actual pillar. When reassembling pay particular attention to lining up the plastic button for seatbelt height adjustment with the metal depression underneath. (Align the pimple with the dimple).

Edit:
Drat, I was too late!

__________________
The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)