So I just removed the centre headrest from my 2018 Disco. It is likely the same for the new facelift model.
From the back seat, fold the headrest up.
1 pull the retaining clip in the right stem out completely. Remove it.
2 push a flat head screwdriver under the left stem cowl trim from the outside left - it pushes a hidden clip inward, I used a plastic trim tool so I didn’t rip the leather.
3 pull the headrest up and out