Mow the grass as short as possible
Water the area lightly to soften the soil
Cut the grass into strips with a spade or sod cutter
Lift and roll up the sod
Remove remaining roots with a shovel or garden fork
Rake out loose grass and debris
Apply a non-selective herbicide if needed
Cover the area with cardboard, plastic, or tarp to smother regrowth
Dig out any new shoots that appear
Dispose of removed grass properly