Dig a “trench” around the grasses you wish to divide and make sure that this exposes the root system. Next, use a shovel to dig out the entire root ball
Depending on the size of the grass clump you are attempting to divide, it can sometimes be done just with your hands. If working with a larger clump, a sharp shovel does best to break apart the clumps. Break apart the roots and the grass clump into the size of your desired grasses.