I'm not sure. Perhaps the simplest would be for the Chinese to convince Kim to step down, or convince his generals to a quiet coup. Black ops to eliminate their nuclear/ballistic capability. Open warfare would not be a good option, even with international consent. 
But a more likely scenario is that Kim does something stupid like cross into ROK or land a missle in Japan or Guam, then we flatten him with shock & awe. Best to ignore him until then (i.e. Don't grant consessions. He'll up the ante & ask for more.).  But make very clear to China & the rest of the world what will happen if/when he crosses that line. It cannot be Pres. Obama's Red Line for Syria.