One of the best ways I've found to remove moss is to use plain, ordinary washing soda. You need to sprinkle the washing soda fairly liberally over the affected area and then moisten the washing soda (or wait for rain before you sprinkle). After a couple of days the moss will be dead and you'll be able to sweep it away with a broom.
If you're into self-sufficiency like me, you can use the dead moss to line hanging baskets before planting. It won't harm the plants because the downward soaking of water due to gravity will wash the soda out of the bottom of the basket and away from the plants above.
Washing soda is not harmful as long as you don't eat it and won't cause long lasting contamination. Washing soda is also very cheap, less than a Euro in the supermarkets.