to make people stop respecting somebody/something

to make people stop believing that something is true; to make something appear unlikely to be true

These theories are now largely discredited among linguists.

This new evidence discredits earlier findings.

These ideas have now been completely discredited.

damage to somebody’s/something's reputation; loss of respect

a person or thing that causes damage to somebody's/something's reputation or loss of respect 

They were a discredit to their country.

LEARNit Dictionary