Sphagnum moss needs cool moist conditions to thrive. When the atmosphere is right, it can spread over your yard. However, simply removing sphagnum moss won't kill it permanently. Before you know it, it will be back and you'll simply have to treat it again. To kill sphagnum moss for good, you will have to dry out its habitat.
Fill the spray bottle. Cover the bottom of the spray bottle with one inch of powder or liquid tide. Then fill it the rest of the way with a 10% bleach solution.
Spray all patches of sphagnum moss liberally.
Wait 24 hours. If the sphagnum is still alive, re-spray it. Repeat until all of the sphagnum is dead.
Remove the dead moss.
Clear any overhanging foliage that prevents direct sunlight from reaching areas where sphagnum moss grows. This will help dry out the area and keep it from growing again. And if possible, reduce the amount of moisture in the area.