hmm, neither link has images for me now, weird! Anyway, let us know how you get on .
Weird, the pictures aren't downloading for me either now, oh well.
I removed mine a while back and I thiiink there's a plastic tab on the other base that you have to push in
Indeed there is a retaining clip, I used a match stick to press it in and then pressed the locking button on the other one and pulled the headrest up and off
The retaining clip and where you need to press it is arrowed: