Take off the vent window disc using a hooked bit of wire, then take off the plastic trim from the door release lever and the slotted head screw there.
Undo one or two large phillips head screws from the underside of the armrest. Use a small phillips in the vertical position to remove the chrome plastic bit at the top of the armrest, exposing a large horizontal phillips that ties the armrest to the door, which you also remove. The armrest will come off.
Remove the ashtray, then the two small screws holding it to the door.
There are maybe ten plastic clips holding the vinyl covered door panel to the door. Gently pry the door panel away from the metal door. Some of the plastic bits may break, no problem, they are inexpensive and readily available and I think VW uses the same ones. If the backing for the vinyl is bad, the plastic bits may break through which is a slightly larger problem as it suggests the pressboard panel may have gotten wet, and will need to be dried and repaired. I long ago replaced at least one of my backing panels with 1/8" thick mahogany ply and varnished it for water resistance.
Once the vinyl covered panel is off, the wood will be in your hands. It's a snug fit around the ashtray.
The door wood is not a complicated piece and is easy to recreate by a person having modest wood skills, some patience, a few common tools, and some varnish. You can use exotic wood for recreations, or dummy up a replacement and vacuum some fancy veneer on.
