We don't have synonyms for detune yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are petune and retune.
(v) :
(music) To intentionally lower or raise the pitch produced by a musical instrument, often to produce sounds not normally possible, or to reduce tension in a stringed instrument for the purpose of shipping or maintenance.
(v) :
(engineering) To alter the resonant frequency of a tuned system so that it is slightly different from a specified target frequency.
(v) :
(music) To intentionally lower or raise the pitch produced by a musical instrument, often to produce sounds not normally possible, or to reduce tension in a stringed instrument for the purpose of shipping or maintenance.
(v) :
(engineering) To alter the resonant frequency of a tuned system so that it is slightly different from a specified target frequency.