不要管与自己无关的事。Don't interfere in what doesn't concern you.别参与和自己无关的事.Do not meddle in things that do not concern you.与专业无关的事,他什么也不知道.He knows nothing of unprofessional matters....

“无关的”的英语可以翻译为：irrespective of，[法] irrelevant，removed，unconcerned，irrespective ...