throw the baby out with the bathwater
Definition from Wiktionary, the free dictionary
From a German proverb that dates to 1512. First recorded by Thomas Murner in his satire Narrenbeschwörung. First appeared in English when Thomas Carlyle translated it and used it in an 1849 essay on slavery.
- (idiomatic) To discard, especially inadvertently, something valuable while in the process of removing or rejecting something unwanted.
- They cancelled the entire project because the new management didn't like the prototype, but I think they threw the baby out with the bathwater.
(idiomatic) to discard something valuable