Murder Your Darlings Definition

verb

In writing books or articles, to delete text of which one is especially proud with the aim of improving the work as a whole. More generally, to destroy , especially with conflicted motives, things or persons of which one is fond .

Wiktionary

Origin of Murder Your Darlings

Possibly first used by Arthur Quiller-Couch (1863-1944) during a series of lectures at the University of Cambridge, later published in book form as "On The Art of Writing". (Arthur Quiller-Couch: On The Art of Writing, Lectures Delivered In The University of Cambridge 1913-1914, Cambridge University Press, 1916).

From Wiktionary