In order from mild to rude: Please don't worry about it. It's nothing for you to worry about. It's not your concern. Mind your own business. Mind your own beeswax. Keep your nose out of it. Butt out! I am sure that is as far as I want to go and as far as you want to learn about the rude possibilities for this.

I have never heard the phrase 'It's none of your concern'. The usual phrase with 'concern' is 'It is not your concern' which is actually a polite and helpful thing to say. It's means 'It's OK. You needn't worry about this'. If you are having an argument with friends, you could say 'It's none of your business' ,if you want them to stop interfering in your affairs.

None of your business But I agree with Azalea, and the tone is also important and can determine if something is rude or polite :)