To disparage or belittle someone or something. He tends to derogate his colleagues' achievements to make himself look better.
To depart or deviate from (a rule, standard, treaty, etc.), especially with official permission; often used with the preposition “from”. Under emergency powers, governments may derogate from certain human-rights obligations.
To detract from or diminish the authority, value, or reputation of something; usually followed by the preposition “from”. The scandal derogated from his otherwise impeccable record.