"Root rot" is a misnomer. In most instances, it is really the suffocation of roots because they surrounding soil is so dense or so saturated that there is no oxygen available to the roots. It is not a disease or fungus. Removing dead roots has no effect one way or the other.
The only possible cure is to allow the soil to dry out sufficiently for oxygen to penetrate around the roots regularly. Roots need regular doses of oxygen as much as they need water.
Sometimes, plants don't show significant symptoms until the roots are already seriously compromised. At that point, even allowing the soil to dry out may be too late to salvage the roots and the plant.
