Seems like it was brought up as an aside on a thread with a different topic.
My memory is drawing a blank (again) and it's drivin' me nuts !
On the other thread on this topic, sentiment seems to be running about 2-1 in favor of the idea that this was Trump’s call, part of his promise to “drain the swamp.” The minority view (which is my view) is that this order came from Obama, and was a petulant move to weaken security at a critical moment.
“Commanding General of D.C. National Guard to be removed from post (at 12:01pm Jan 20th)”