Expurgation means removing parts of a written work that are offensive or objectionable. After your fussy teacher's expurgation of your short story, you might hardly recognize the tame prose that's left.
Some famous works of literature undergo a thorough expurgation by well-meaning editors who want to make the stories less upsetting for younger readers. Others see any kind of expurgation of a book as censorship — the unfair suppression of artistic expression by some authority figure. Expurgation, with its fifteenth century meaning of "a cleansing from impurity," has a Latin root, expurgare, "to cleanse out, purge, or purify."