Leaving or quitting a club (e.g., a school club); used as a noun and in the verb form '退部する'.
体調不良のため、彼は今月末で退部することになった。
Due to poor health, he decided to quit the club at the end of this month.
新しい顧問の方針に反発して、数名が退部を申し出た。
Several members submitted requests to quit the club in protest of the new advisor's policies.
退部届を部室に提出して手続きを済ませた。
I submitted a club resignation form to the club room and completed the procedure.