Negiah is the action of touching (someone of the opposite sex). It's a noun.
Sounds like a small child telling his/her mother " I'm not touching ! " after being told "do not touch" :)
Hmm... not really. "I am not relevant" would be something like: "אני לא קשור (לזה)" or "אני לא נוגע לעניין" (which sound a bit awkward) or (shifting the subject): "הדבר לא נוגע לי"