These trims are in three sections:
Remove the door mirror first:
Second remove the outer windows trim and rubber seal that pushes against the glass - I removed my chrome ones by sticking two layers of masking tape along the top edge of the door, then carefully prized up the section of trim, moving from B pillar to A pillar. Do very small sections at a time then move forward until it lifts off. There should be an thin inner plastic liner that fits inside the trim section this protects the paint and also acts as a kind of spacer so that when the trim is squeezes against it and the top lip of the door it all stays in place.
Next remove the long top section, these clip on all the way round, again use masking tape to protect surfaces that I was levering against and a small flat bladed screwdriver to prize off carefully. (I worked from front to back this time)
Finally remove the upright section in a similar fashion.
Taking your time and protecting the surfaces are key to this job, especially with the black trim as you don't want to chip that!
It's not as scary as you'd imagine :-)