let off on (someone or something)
To decrease the amount of pressure, either physical or figurative, applied to someone or something. Let off on the brakes a bit when you're coming to a red light—you don't want to come to a stop that fast. The Eagles refused to let off on the Patriots' offense for the entirety of the game. You should really let off on Steve for a while—his divorce has been really hard on him.
let off on
Informal To cause to diminish, as in pressure; ease up on: Let off on the gas so that we do not exceed the speed limit.