He doesn't need a reason, shitforbrains. He can fire her just because he doesn't like her or even if he just want's someone else in that job. Ambassadors serve at the pleasure of the president, period. I have a friend (Gary Grappo) that was once ambassador to Oman under Condoleezza Rice and George W Bush, when the administration turned over under the Obummer administration he was reasigned to some shit post in Iraq and departed the state department shortly thereafter. Try reading the constitution before opening your mouth again. That is if you can read and comprehend what you read.