Chipotle's founder could be the biggest problem the struggling chain's new CEO has to tackle (CMG)

Chipotle's founder, Steve Ells, is stepping down as CEO, and Taco Bell's CEO Brian Niccol is taking over as chief executive. 
The new CEO's success will be "directly related" to the freedom he is given."Niccol will likely face an uphill battle in uprooting some of that heritage, as he’s stepping into a role occupied by a founder for the past 25 years," one analyst told Business Insider. 
 
Chipotle's new CEO's biggest challenge could be taking on the chain's founder.&nb