Interesting,  quite a few of Mr. Trump's upcoming appointments are actually preceded by a "Firing".  The major cabinet appointments like State, and Defence automatically replace an appointee the minute Trump takes the oath.   Other appointments, like FBI, are normally for "x " number 
years, regardless of who is President.  (Remember, it last term, he had to fire the standing FBI Director)  Difference is now, he's not wasting the time.