Moss typically grows where grass has a difficult time growing...damp, shady, areas are ideal for moss growth. If you have moss, many times the alternative is dirt, so be glad you have some moss!
There are natural products that will kill moss, but unless you can get grass to grow, there’s no point in killing the moss. If the moss bothers you and you’d prefer grass, you’ll need to make conditions more conducive for grass growth. Consider soil testing and balancing the soil, removing trees that are providing shade, and possibly adding some drainage.