unlearn

动词 unlearn:

1. try to forget; put out of one's memory or knowledge
2. discard something previously learnt, like an old habit

1. He was not unlearned in history.
   他对历史并非无知。
2. You must start by unlearning all the bad habits your previous piano teacher taught you!
   你得先改掉以前钢琴老师教给你的一切坏习惯！