demote (v.)youdaoicibaDictYouDict[demote 词源字典]
1881, American English coinage from de- + stem of promote. Said to have been Midwestern in origin.
Regarding an antithesis to 'promote,' the word universally in use in Cambridge, in Harvard College, is drop. The same word is in use in the leading schools here (Boston). I hope I may be counted every time against such barbarisms as 'demote' and 'retromote.' [Edward Everett Hale, 1892, letter to the publishers of "Funk & Wagnalls' Standard Dictionary"]
Related: Demoted; demoting.[demote etymology, demote origin, 英语词源]