I was wondering if it was possible to disable the “For each kanji, choose whether the reading is onyomi or kunyomi” quiz type without actually disabling either relevant vector. I want to keep the respective reading quizzes, but not the “which is it” type of quiz.
If I understand right, you want to continue to be quizzed on the on and kun readings? It's alright, the kanji -> on/kun and on/kun -> kanji questions will be there even if you disable that.
Go into Kanji Schedule -> Click Schedule Options (Gear icon) -> click Readings -> scroll down to Advanced question types -> uncheck "Onyomi or Kunyomi?" -> check any quiz types that you do want