How do i get rid of burnt smell from kheer?
Use a nonstick saucepan. While there can still be some caramelization, at least burnt stuff will not stick and get burnt further.

Also, consider using the oven if you have one: Preheat the oven to 110-120°C, while bringing the pot and kheer up to temperature on the stove. Place the hot pot in the oven - this will keep it at slow cooking temperature but make it impossible to reach sufficient temperature to quickly burn anything....