i'm only really going by whats on the golf has when its only woofer/tweeter in door, the cross over for the OEM tweeter will only be a small capacitor, so if you find the tweeter and eliminate the 2 wires going to that, the other 2 in your pic will be the supply wires from the stereo.
also if you look closely at the connector and speaker in your pic it should have a plus and minus sign on, if you need the full wiring diagram, let me have the year and the engine code from your car and what model of stereo it has in it and i'll send you a pdf of the VW wiring from a program called Elsawin what vw use at the dealer.