If large patches of clover have invaded your lawn, physical removal is the first step. Use a spade or a sod-cutter to dig the clover patches out, roots and all. Another option is to cover the clover patch with a tarp for about two weeks, and then dig out the dead plants. When the area is clear, lay in 2 to 3 inches of topsoil, and replant with grass seed.
A person can dig out small patches of clover with a knife, but many gardeners consider a minimal amount of clover to be an asset to a lawn. Commercial blends of grass seed often include clover seed, because clover adds nitrogen to the soil and helps crowd out taller, less desirable weeds. Clover blossoms also attract pollinating insects, which are beneficial to nearby flower and vegetable gardens.
For lawns that are overrun with clover, some organic gardeners use sugar. LoveToKnow Organic suggests sprinkling 4 to 5 pounds of sugar onto clover, then watering until all the sugar has dissolved. While this does not immediately remove the clover, it kills the roots so the clover doesn't return next year. Another additive used by organic gardeners to suppress weed growth is corn gluten meal. Spread about 20 pounds of corn gluten meal for every 1000 square feet of lawn, and water the area well.