degrade

To lower in value or social position.

Fred degrades himself by his behaviour.

[…] [William] Prynne was sentenced by the Star-Chamber Court to be degraded from the bar, to stand in pillory at two places in London and lose an ear at each, to be branded on the forehead, to pay a fine of five thousand pounds, and to be imprisoned for life.

To reduce in quality or purity.

The DNA sample has degraded.

To reduce in altitude or magnitude, as hills and mountains; to wear down.