turn (one's) back on (someone or something)

To ignore, disregard, or exclude someone or something; to abandon, give up on, or forsake someone or something. It's clear that the company has turned its back on customers. After becoming a successful writer, Jim turned his back on all the people he used to know back home.

Deny, reject; also abandon, forsake. For example, I can't turn my back on my own daughter, no matter what she's done, or He simply turned his back on them and never gave it a second thought. [c. 1400] Also see when one's back is turned.

COMMON If someone turns their back on you, they ignore you and refuse to help you. We appeal to this conference — do not turn your back on the poor. Our job is to protect children and we can't just turn our backs on them.

COMMON If you turn your back on something, you reject it or stop being involved in it. He had turned his back on his Communist past and formed a completely new party. The organisation says that young people are increasingly turning their backs on marriage.

To reject; also, to run away (from a fight). Emerson used it in the first sense in his famous Transcendentalist poem, “Brahma” (1857): “Find me, and turn thy back on heaven.” Tennyson used it in the second sense in “The Revenge”: “Let us bang these dogs of Seville . . . For I never turn’d my back upon Don or devil yet.” The second figurative meaning is the older one, dating from about 1400; the first began to be used about 1600.