They are secured with a 22mm nut.
Remove the wheel on the side you need to replace, then remove the wheel arch liner, if it's the nearside you will need to remove the horn, if it's the offside you will need to remove the carbon canister.
You will then need to remove the pipe from the back of the jet, it just pulls off. Then carefully use a 22mm socket with a long extension to remove the securing nut, carefully remove the chamfered washer from behind the nut, then the washer jet just pulls out.