A pedestal is a base or foundation that supports something like a statue or work of art. Think of the Lincoln Memorial in Washington D.C. where a statue of Lincoln sitting in a chair is raised up on a huge pedestal.
Think of the physical stand or support when you use pedestal figuratively to mean a place of superiority. If you put someone on a pedestal, you honor that person or place him or her above you, as you might a piece of valued art. If you want to knock someone off his or her pedestal, you think that person is too arrogant and you want to do something to humble him or her.
