Knock somebody off their pedestal/perch
Definition 1 of 2
Pro Tip 1/3Ideal Image Shattered
Use when someone idolized is seen as flawed or ordinary, shattering the perfect image. 
The scandal really knocked the mayor off her pedestal in the eyes of the public.
Pro Tip 2/3Figurative Fall
The phrase is figurative; no one's physically on a pedestal or falling from it. 
The champion swimmer was knocked off his pedestal when he lost the race.
Pro Tip 3/3Emotional Impact
It often expresses a mix of disappointment and realization. 
After the interview, people saw the flaws and knocked him off his pedestal.