This shows there presence does not affect you one bit and if you haven’t introduced yourself already – go ahead and do so.
Keep it short, blunt and straight to the point
No need to speak in long essays, last thing you want is to hear their voice excessively, which even that may irritate you
Try to be nice to them and try a compliment even if it means you are faking it… just to see what type of reaction you receive
Avoid them as much as you can
If you want to come across as not wanting them around then the best thing to do is trying not to engage, the above steps are to ensure you act accordingly if approached or you feel you need to say something just smile, try to act normal and see the type of responses you get along with the persons body language when compared to when they’re with someone else… if it is different we guess they may have something against you too.