Moss is a pretty addition to the landscape if it's growing in the proper place such as on rocks in the landscape. If the moss is growing on walkways, stepping stones or gravel paths, however, it isn't as safe. Moss is slippery, causing people to fall or gravel to shift under foot. If you have a gravel path or walkway, you can easily kill the moss by doing a few simple things.
Look around the walkway at adjacent bushes and plants. Trim back bushes so they aren't blocking air circulation or casting shadows on the gravel. Use loppers and make cuts just in front of a leaf or needle on bush branches. Good air circulation is the enemy of moss and algae.
Cut tree branches overhanging the walkway. Moss loves cool, shady spots. By taking out the branches and letting in the sun, you are making the gravel environment less hospitable. Use a tree trimmer to snip or saw the branch. Cut at an angle in front of a leave node or fork.
Mix equal amounts of salt and water in a spray bottle. Spray the gravel low to the ground so you don't get the mist on other plants. The salt will kill most vegetation and the moss as well. As a bonus, salt tends to keep vegetation from growing back in an area for several months. Between the salt and opening up the area, you shouldn't have any more issues with moss.