Moss is considered a weed. It can pop up in areas of your lawn where growing conditions for grass are not favorable. Since moss is not attractive, most homeowners want to get rid of it. You can kill moss much the same way you kill any other type of weed, but you will have to physically remove it once it dies. You can then plant grass seed to take the place of the moss.
Mix an herbicide that contains the active ingredient iron sulfate with water. The amount of herbicide and water can be found on the herbicide's product label. According to Oregon State University, the average combination is 3 oz. of iron sulfate in 5 gallons of water. It will cover 1,000 sq. ft. of lawn.
Use a garden or backpack sprayer to spray the herbicide over the moss on your lawn. You want the moss to be completely covered with the herbicide, but not dripping.
Wait for the moss to die off completely. This may take a few days.
Rake the moss up into a pile. Put on a pair of plastic gloves and bag the pile of dead moss.
Spread grass seed over the area that is now bare, and then water the area so that the ground is moist. Then keep the ground moist until the grass seeds begin to sprout.