From Longman Dictionary of Contemporary Englishbe done with itbe done with it (also have done with it British English)FINISH/COME TO AN END used to tell someone to stop thinking about or trying to decide something because they have already done this enough Just buy it and have done with it! → done
Examples from the Corpus
be done with it• He might as well capsize the dinghy and be done with it.• If you're running Windows, update your system to the latest version of Internet Explorer and be done with it.• In fact, the mayor could submit a written report to the Board of Supervisors and be done with it.• Nigel Lawson showed what could be done with it.• Once a cancer is detected there is no consensus as to what should be done with it.• There was so much anger in her she could not see what might be done with it.• Call it a freak accident and, hopefully, be done with it and race on.• The goal of reading is to be done with it, to be able to close the book and play. 