A typical homeowner can have many reasons to kill their lawn. Maybe your lawn is in shambles, or maybe you want to put in a garden or flower bed where part of your lawn currently grows. To effectively do those things, you must kill off the existing grass. Grass can be killed with a non-selective herbicide like Roundup. One or two applications of the herbicide will effectively kill all the grass. Non-selective herbicide rapidly breaks down in the soil, so the area killed can be planted again immediately.
Mix up the correct amount of non-selective herbicide concentrate and water and fill your pump-up sprayer. Read the bottle for the correct mixing ratios.
Spray the grass you want to kill with your pump-up sprayer. Getting the grass blades moist is sufficient to kill them.
Apply a second round of non-selective herbicide a week later to kill any remaining grass in the area that wasn't killed with the first application.