This is a basic how-to for removing the bottom plastic plate on your 1968-69 (and perhaps later) headrests, in preparation for covering them.

I purchased my headrest covers from USA Parts Supply for about $25 per pair. Before my upholsterer would attach them (by glue - there's no frame to staple the covers to), he wanted me to remove the bottom plate. This can be done fairly easily by pulling out two plastic pins (see below). These are non-reuseable pins, though you might salvage them if your very careful. The major thing is to avoid scarring the plate itself.

These are the heads of the two pins you need to remove.

I slid a piece of cardboard under the head to help protect the plastic plate.

You can depress the entire plate, giving you enough of an exposed head to grasp it with pliers.

A slightly-mangled pin. Replacements have been available from Year One for $1.75 each.

Once the pins are out and the plate is off, two metal disks are revealed.
If replacement pins are not available, it should be easy to tap the out or to drill them out enough to allow the use of pop rivets.

A close up of one of the above-mentioned anchoring disks.

Original on the left, covered (but just slipped on, not yet fitted or glued) on the right.

Cover manufacturer's label.