Cut the ornamental grass stalks in small sections with a hedge trimmer, starting from the top. Move the trimmer from side to side and cut a few inches off the grass for each stroke until you reach the bottom.
Hold as many grass stalks as you can in one hand and then cut them off at the base with pruning shears, a sharp knife or a machete. Repeat until you have cut all the stalks off. Arrange the stalks together on the ground and cut them up into small sections with the knife or machete.
Cut the ornamental grass stalks from the stump with a knife, then lay them flat on the ground. Run a lawnmower over them until they are as small as you wish.
Cut the stems with a trimmer or machete. Feed them into a shredder.