First of all, you should observe that how much area of your yard is covered with crabgrass. The crabgrass spreads very fast and you have to remove it immediately after identifying it as it will keep the grass of your yard healthy and its growth will be good.
After identifying crabgrass in your lawn, you should pull out the crabgrass from the ground of your yard. Make sure you pull it out from its roots which will help you not to see it again growing in your yard.
Another way of removing the crabgrass from your yard is that water your yard which will make the soil soft and pulling out crabgrass will be quite easy. The softness of wet soil will help in pulling out the crabgrass from its roots.
If you observe that crabgrass has just started to appear in your yard then spray pre-emergent herbicide which will help in eliminating the small sized crabgrass at its initial stage.
However, the spray of herbicide will not produce better results if the crabgrass has grown well. In this case, you have to pull it out from the roots.
After pulling out crabgrass from its roots, you need to throw it away from your lawn or yard. Make sure you have also removed all seeds of crabgrass from where you have pulled it from the ground.
You should immediately take the seeds of grass to fill the empty spots from where you have pulled the crabgrass. It will help you to grow the desired type of grass in your yard.
For avoiding the growth of crabgrass, you should shirk over watering your yard because the excess of water always helps in growing crabgrass.