Is this crab grass ?
It looks like Poa annua or annual bluegrass, a cool season weed. That weed will be dying on its own with the arrival of warm weather. It sprouts in early fall and grows through the cool season. The best ways to prevent it are to build a dense turf that blocks sunlight from reaching the soil and if needed to use a pre emergent weed control product in late September to prevent the Poa annua from germinating.