step something down
phrasal verb with step verb [ I + adv/prep ] uk/step/ us/step/ -pp-
减少，降低（数量、供应量或速率）
to reduce the amount, supply, or rate of something
The doctor has said that I can start stepping down my medication in a few days' time. 医生说我几天后可以开始减少用药量。
This device is used for stepping down the voltage. 这个装置用于降低电压。