From FoxNews...no one else has details yet lol. or they just don't want to print them because this is non-news-breaking. 

"Bannon was put on the NSC’s “Principles Committee” as check on former National Security Adviser Lt. Gen. Mike Flynn to make sure Flynn carried through with a directive to depoliticize the NSC, a senior administration official told Fox News.

Bannon only attended one meeting of the Principles Committee and Flynn was fired from his role in early February after misleading Vice President Mike Pence about conversations he had with a Russian official.

With H.R. McMaster now established as National Security Adviser, Trump saw no need for Bannon to stay on the committee as a check on Flynn, the official said.

Bannon is still permitted to go to NSC meetings."