Rhubarb is a plant that produces green or reddish-green stalks suitable for making pies, jams, or fruit crumbles. A relatively hardy plant, rhubarb grows quickly and is resilient even in acidic soil and direct sun. But because it grows quickly and is a relatively hardy plant, you may find that you need to kill off some or all of the rhubarb plant as it grows and begins to take over other sections of your garden.
Over-water the rhubarb. Over-watering leads to crown rot, which can kill off even the most stubbornly entrenched plant system.
Reduce the soil's pH. Because rhubarb grows best in slightly acidic soil, lowering the pH can create a less-than-ideal environment for the plant. Organic gardeners recommend using pure sulfur or flowers of sulfur to accomplish this.
Dig up the plant and pull up the entire root system of the rhubarb plant with a shovel or garden spade. According to RhubarbInfo.com, very old rhubarb plants can have root systems that span over 3 feet in diameter, so make sure to carefully examine the area so you do not overlook a root crown that could grow back.