verb

reduce to a lower grade, rank, or level of importance.

some jobs had gradually been downgraded from skilled to semi-skilled

demote,lower,lower in status,reduce/lower in rank,reduce in importance,relegate,bust,degrade,disparage,denigrate,detract from,run down,decry,belittle,make light of,minimize,defame,bad-mouth

noun

an instance of reducing someone or something’s rank, status, or level of importance.

downgrades by debt-rating agencies outnumber upgrades by five to one