McMaster successfully had Bannon removed from Trump’s National Security Adviser meetings, and also had previously removed a Bannon aide, who attended in Bannon’s absence.
I believe it was General Kelly, as Chief of Staff, who gave Bannon his walking papers, since Bannon was a White House presidential political adviser, ensconced in the West Wing.
I just read the first section of Bannon’s bio on Wiki- I like him even more now, (will finish it later) and Wiki confirms to me that we need him and more like him on Trump’s staff.