WASHINGTON — In an interview on Monday on “Good Morning America,” Cliff Sims, a former White House aide promoting a tell-all book about life inside the West Wing, wanted to make clear that he had left his job on his own terms. Anticipating pushback from the White House, he told George Stephanopoulos, the host, that he had brought his resignation letter along to prove it.

White House aides have been telling reporters for weeks that Mr. Sims was fired, but did not want to comment about him on the record. A former official noted that Mr. Sims was “instructed to leave due to a major security breach” — a reference to what Mr. Sims said was the time he recorded President Trump in the White House on his government phone and then emailed those files to himself, but insisted that was not the reason he left.

The Trump White House has set a record for turnover — more than double that of President Barack Obama’s after two years in office — but somehow leaving it is never simple.

Omarosa Manigault Newman, a former communications adviser, was abruptly fired in the Situation Room, though she said Mr. Trump later claimed that he knew nothing about her dismissal and she denied that she had abused the White House car service, as aides claimed. Lesser known aides, like Sean Cairncross, a former senior adviser, have announced their resignations and then lingered for months in a building next door to the White House, continuing to collect government salaries while waiting for their next gig.