Removing an existing lawn is the most efficient way to replace the lawn with new seed or sod when weeds and other health problems have troubled the lawn. Simply re-seeding over an existing unhealthy lawn will not result in the beautiful lawn you would like to achieve. This process can be lengthy but rewarding after the new lawn has been established.
Spray an herbicide containing glyphosate to the entire area to be removed. Do not use the spray if rain is expected within 48 hours after application. The soil and grass should be dry upon application and remain so for two days. The herbicide may take seven to fourteen days to kill the grass and weeds in the lawn, depending on the climate. Warm and dryer climates will see results more quickly than cool moist areas.
Mow the dry grass close to the surface using the mower's lowest blade setting. The blade should settle just above the soil surface. Rake all the clippings and debris from the area. A thatching rake will assist in removing the most debris and loosen the soil. Repeat this process until the area is free of debris and all grass and weeds have been removed.
Till the soil with a roto tiller, adding amendments to enrich the soil health before re-seeding or laying sod in the area.