own up

to admit that you have done something wrong:
No one has owned up to stealing the money.
(Cambridge Advanced Learner's Dictionary & Thesaurus からの own up の定義 © Cambridge University Press)

アメリカ英語辞典
to tell the truth or to admit that you are responsible for something:
A young nurse looked at the two men and waited for one of them to own up.
(Cambridge Academic Content Dictionary からの own up の定義 © Cambridge University Press)

- Cambridge Dictionary