What is the lowest possible rating you can achieve (if any)? This question comes from a lack of understanding of how ratings work.
What is the lowest rating you can get ( or does it never stop decreasing )?
If the Elo system is implemented in its purest form, there is no theoretical lower limit for a rating. 

Practically though, every chess organisation implements its rating system a bit differently and often there are rating floors that constitute the lowest possible rating. 

The USCF for example seems to have a rating floor of 100.