From Longman Dictionary of Contemporary Englishlet him/her/them etclet him/her/them etcused to say that you do not care if someone does something they are threatening to do ‘She says she’s going to sell her story to the newspapers!’ ‘Well, let her!’ → let
Examples from the Corpus
let him/her/them etc• He would not rush the boy, he had to let him come to him.• Then let her do it for the Junior League.• I had once made the mistake of letting him do this.• I also owed Maggie the courtesy of letting her know I didn't need her to do my legwork any longer.• Of course, Kate could have shrugged and let him stew in his own juice, or lack of it.• I stood there, thinking to myself, Okay just let him wear himself out. 