Use a non-selective herbicide labeled for grass control, following the product instructions exactly
Apply boiling water directly to small patches of grass
Smother the grass with cardboard, landscape fabric, or thick mulch to block sunlight
Dig out the grass, including the roots and rhizomes, with a shovel or sod cutter
Solarize the area by covering it with clear plastic during hot, sunny weather
Repeatedly cut or mow the grass very short to weaken it over time
Adjust soil conditions only if appropriate for the replacement plants you want to grow
Hire a licensed lawn or weed-control professional for large or difficult infestations