Though many people find the look of a mossy brick terrace very charming, in rainy weather, that attractive moss can easily become slick and dangerous.
Fortunately, there are products on the market that can easily and safely rid your property of moss; one good choice is Safer's Moss and Algae Killer. Available in many garden centers, this spray is made of naturally occurring, biodegradable fatty acids.
To use, first wet the surface of the brick with a garden hose, then spray liberally with the product. It will require a few days to work, so try to apply it when there is no heavy rain in the forecast. As the moss and algae begin to die, they will discolor and fall off on their own.
Another product you might try is garden lime. By treating the soil in the cracks between bricks with lime, you will make it more alkaline. Moss likes acidic soil, and therefore won't grow in the treated soil. Always wear gloves and a mask when handling lime to avoid contact with dust particles. Sprinkle the lime heavily over the moss, and allow a few days for the moss to dry up and die. Once it does, you can simply sweep it away.