Just behind the alternator pulley, there should be the tensioner pulley, you should be able to move that with a spanner (it's on a strong spring) and hold it to release the tension and remove the belt.
In relation to your other post, you can test to see if the pulley is ****** by moving the steering while the car is stationary, the vibration will be louder and the steering pump will make a noise. I replaced the pulley on my golf recently, it's not too bad a job but you need a special tool.