How is “kill off” used?

In Circle (2015), one line is: “kill off certain people.”

Which movie is “kill off” from?

The clip at the top of this page is from Circle (2015).

kill off certain people.

5 作品で登場 · 1 本目

句動詞

to make a lot of plants, animals, etc. die

5 本の映画に登場

1
kill sb / sth off
to make a lot of plants, animals, etc. die
Some drugs kill off useful bacteria in the user's body.
2
kill sb / sth off
to stop or get rid of sth
He has effectively killed off any political opposition.

定義：Oxford Advanced Learner's Dictionary 第 9 版