Provided it will not harm any nearby plants, carefully pour boiling water over the joints. The next day, you can remove the dead moss easily using a joint brush.
Damp and shady joints provide the ideal location for moss. To stop it from growing, refill the joints each season, alternating between sand and gravel. This will not only remove moss spores and weed seeds regularly, but will also allow better drainage of surface water, depriving the moss of a crucial source of growth.
Salt and saltwater are not suitable for combating moss because salt accumulates easily in the soil and harms it. It should therefore be avoided. Vinegar, on the other hand, does not pose a problem, as it is organic and decomposes quickly.