Although it's not essential, you can remove the front panels first to give you a bit more room to work with.

Front panel removal guide here: removing the front panel

Slacken the mirrors so they aren't pressing on the panel. Some information on how to do this can be found here: removing mirrors. Note: if you have manual mirrors, you don't need to free the adjuster from the cover.

Open the window fully and pull away the top rubber strip.

Close the window fully.

There are three clips at the top securing the door skin to the top metal bar, they will slacken off when you press you knee in the centre of the door, unclip all three, open the door and slide it down and off.

Refitting is reverse of removal, pay extra attention in whether the window should be up or down while you are doing in this.

Tip: Whenever you put you knee in the door ensure the window is fully closed.