take down a notch

verb2

1. •
   To cause a person's or group's self-esteem or importance to be decreased.

   • Confident and near-cocky for the second straight debate […] [McCain] easily deflected Romney and Giuliani attempts to take him down a notch. — 2008
2. •
   To cause the quantity, degree, or intensity of something to be decreased.

   • [M]any travel companies are holding prices steady or taking them down a notch. — 2008