The phrase "none of one's concern" means that something is not important or relevant to a person. It implies that they should not worry or get involved in that particular matter.
Sentences with «none of one's concern»
None of the concerns in the survey questions are of concern to me. (goodereader.com)
Further information on this topic is simply none of your concern. (babygaga.com)
And of course, with guaranteed loan approval none of the concerns over application rejection can be put aside. (badcreditloanservices.com)