Water the grass for three days before applying an herbicide to encourage growth. Killing vigorously growing grass with herbicide is easier, because dormant turf does not absorb as many of the toxic chemicals.
Spray the grass with a broad-spectrum herbicide that contains glyphosate. Glyphosate impedes grass' ability to produce proteins and leaves little soil residue. Cover ornamental plants with plastic when spraying glyphosate. Broad-spectrum herbicides kill any type vegetation they contact.
Reapply the herbicide in 10 days. You know grass is dying you see discoloration, wilting and browning.
Rake up dead grass blades. Remove all vegetation before replanting. Use a tiller to break up the bare soil.
Throw away or burn up the dead vegetation. Do not compost herbicide-treated grass blades.