If it is removable (as opposed to being a piece of the panel which is just textured and coloured differently), I would assume that it is attached to the panel with the intention it won't (normally) be removed (probably plastic-rivets - basically plastic stumps on the piece that are melted and spread to secure it to another).
So I would think you will need to remove the whole door panel - unfortunately I don't have any like that so can't offer any advice on whole panel removal. If it is plastic rivets - you might have to come up with an alternate fixing method after the wrap.
If no one is able to give details specifically about that part - I would be inclined to remove the entire panel anyway to find out how it is attached (as knowing where clips are, if it uses those instead, makes it easier to release them - esp. if you are pushing them from the inside). If you take some photos while doing so you could probably throw them up with a short 'how-to' for future reference.
