As her post as deputy national security adviser, Ricardel was number two to John Bolton and sat in a number of briefings alongside the president.
Nielsen is a close ally of Trump's chief of staff, Kelly, who preceded her at the Department of Homeland Security, and it's possible her departure may lead to his.
She went on to hold positions in three Republican administrations, working in the departments of State, Defense and Commerce, as well as acting as an aide to then Republican Senate leader Bob Dole.
Ms. Ricardel, an ally of national-security adviser John Bolton, began her service in the Trump administration as associate director in the White House Office of Presidential Personnel, then moved to the Commerce Department previous year.
Melania Trump issued a statement on Tuesday saying that Ricardel should be removed from her position.
According to the Wall Street Journal, the first lady's office believed Ricardel was behind negative stories and was known to not get along with Secretary of Defense James Mattis and at times sought to undermine him from within the White House.
Maddow updated her viewers that was announced that Ricardel would be leaving the White House. A member of the Council on Foreign Relations, she had joined the White House in May this year.
But Ms Sanders didn't say what Ms Ricardel's new job would be, and didn't respond to follow-up questions.
Melania Trump has joined the ranks of weaponized First Lady, and it may be just what the country needs.
And Katherine Jellison, a historian specializing in first ladies at Ohio University, warns that Melania risks losing her best attribute - her coolness "in contrast to her husband's bombastic personality".
Kelly reportedly came into conflict with the first lady over staffing issues, including his refusal to promote some of her senior aides.
McBride, executive in residence with the Center for Congressional and Presidential Studies at American University, said most White House employees know - or should know - the power and authority of first ladies.