Remove the plant from its pot
Gently wash off all soil from the roots
Cut away all brown, mushy, or black roots with sterilized scissors
Keep only firm, healthy roots
Trim damaged leaves and stems if needed
Disinfect the pot before reuse
Use fresh, well-draining soil
Repot the plant in a pot with drainage holes
Water lightly after repotting
Let the soil dry out before watering again
Move the plant to a spot with proper light and airflow
Reduce watering frequency going forward
Check the roots regularly for further decay
Discard severely rotten plants if recovery is unlikely