Welcome
You've got to get the door card off to remove it - dead obvious once it's off the car.
To remove doorcards on a 3 door, (imagine 5 door is the same) - there's a screw by the tweeter cover covered in felt - you'll need a stubby screwdriver.
Those two screw as seen in the picture under the bit of door trim you've removed need undoing.
Then use a screwdriver wrapped in a towel or something to start prising the door card away from the door - start at the lower right and work your way around. They're pretty strong, but it's just a series of clips holding it together. Then disconnect anything electrical and lift off, although you may need to mind the security strip at the top by the window.
In your case, you'll need to get the window winder off - I don't know how to do this as I've not come across one on a Polo before.
Very simple though.
Good luck!
