Can a smell kill you? I mean can a smell be so bad that it kills you?

Difficult question to answer! For sure there are a number of chemicals which if you breathe them in will kill you (poisons, biological weapons etc)  and some of those have a very nasty smell. However what I think you are asking is can a non-toxic chemical kill a person purely because the smell is very unpleasant. If so I think on balance the answer is no, and what will probably happen is that the body will "get used" to the smell so it no longer bothers the person.

It's worth adding that our (and any other animal's) sense of smell evolved to detect chemicals that are important for our survival and reproduction - in either a good or bad way. So too has the emotional response we have when smelling things, although this is influenced by learning too. So, it's no accident that dangerous chemicals such as acids smell sour and unpleasant, or that excrement or rotting flesh (which contain parasites and bacteria) smell 'disgusting' and can even cause one to be physically sick. Being driven away in revulsion, and even being sick, are adaptive responses if contact with the substance is dangerous and you may have ingested some by accident. So, it's unlikely that a SMELL could kill you (this being a very maladaptive response to anything!), but if something smells really repulsive then it's a good bet that the substance itself is bad for you.