Use a pen knife to pop the GT badge/horn button out of the wheel, be careful though, its got 4 long prongs and 2 small springs.
Next unscrew the 4 screws you can see through the hole and the rim comes off. Then it's a simple job of removing all the screws at the back of the rim. The only 2 that are a pain to get to are the ones under the paddles.
I'v not done it as im almost guaranteed to break them.