I removed the headliner in my car a few months back and reinstalled it quite recently. but i did this while I had the rear window of the car. so I took it out and put it back through the rear window opening. It’s quite a lot of panels that needs to be removed in order to get the headliner out properly. A,B and C pillar trim needs to be removed. in order to remove the c-pillar the back seat needs to come out along with the rear shelf where the rear speaker sits.
I don’t now if its possible to remove it through the door opening since I’ve never tried it. but be careful if you do since its really week around the sunroof opening.
the headliner piece for the sunroof opening is quite easy to remove through the sunroof opening (up). but in order to do so the sunroof itself needs to be out. I think this is the only way to remove it as well since the sunroof guides and complete assembly is in the way to remove it downwards.
hope this can be of some help