to cause (a person, achievement etc) to seem unimportant or of small value

detract

to show that (something generally believed) is not true (especially with sarcasm)

disprove, ridicule

to cause (a person) to be less moral or less deserving of respect

shame, humiliate

to lower (oneself, also a person) in dignity, reputation

humble, humiliate

to cause (a person) to feel ashamed; lower the dignity or self-respect of (a person)

embarrass, put down

to reduce (something) to the smallest amount or degree

make smaller; underrate