You can’t.
It always shows the peak. You can change how long it holds the peak for from Preferences/Metering/Meters’ Peak Hold Time but that can only be set to between 500 and 3,000ms.
By right clicking in the meter on the mixer you can determine whether the peak line remains on the meter.
I set the hold to as low as possible, the 500ms. The main number though does seem to always stick there, the last peak that it hit. I was looking for a way to turn this off… Guess for now, I cannot. Thank you.