Hedges are commonly used as privacy fencing because they grow thick, close together and tall. If you want to remove hedges from your lawn, you must also kill the root system. The root system for a hedge consists of thousands of tiny roots that are hard to completely remove from the ground. A simple way to kill the root system is to rot it out.
Cut the trunk of the hedge as close to the ground as possible with a hand saw or pruning saw. Discard the hedge.
Drill as many holes into the top of the trunk as possible with a ½-inch drill bit and hand drill. Drill down as far as the drill bit allows.
Hose down the trunk with hose water and pack the holes with nitrogen-rich fertiliser. Wet the fertiliser with hose water.
Place plastic sheeting over the trunk and cover the plastic with wet mulch.
Remove the mulch and sheeting weekly, repack the holes with fertiliser and wet the area using the hose. Do this until the trunk rots and starts to fall apart. When the trunk falls apart, you know the root system is dead.