There is a small button on one of the two fittings on the seat back - push that button, then lift the headrest.
You don't remove the seat-back from the seat, you remove the leather from the seat-back. It's much easier with the seat out and on a bench. You pry up around the edge to remove the leather.
I'd love to see some pictures of your replacements.
Found the hole to realese the headrest retainers Thanks for the instructionsThat is correct. This is hard to explain without a picture... there is a "tang" (like on a phone cable) that is part of the plastic piece and which locks the plastic piece in place. Look down the bore and you can see the tang, it's maybe 1/8" wide and maybe 1/2" long, and it has a small hole in the end. It doesn't protrude into the bore, it is on the wall of the bore. Use a straight pick and stick the tip into the small hole, bend the tang inwards (towards the center of the bore), and then give the plastic bit a stout pull up. It takes some coordination to do all three at once, but it is the only way
As this is an old thread, he has not been on since Oct 2018 and may not answer.@Alschief did you reinstall the little black clips round the leather trim when you reassembled? These are the ones that push down into the channel round the back. I can see that they are meant to hold the cover to the back, but the cover is such a tight fit I wondered if they were necessary?