It looks like crabgrass to me. The simplest way to eliminate it is to not
let it set seed (mow and compost the clippings) or germinate (pre-emergent
herbicide applied in late spring, after cool season grasses have germinated
but before crabgrass has germinated).

Mowing is pretty effective, since the seed is produced on stalks above the
height of a typical lawn. There won't be much to mow except those stalks,
so it may seem like not worth the effort, but mowing pays off the following
year. Mowing alone takes a few years to control crabgrass, until the seed
bank in the soil is used up.

Una