White House deputy press secretary Raj Shah confirmed in a statement on Tuesday that Sadler had quit, but Conway would not say whether her departure was related to her comments about McCain, claiming she could not comment on personnel issues.
She stayed on staff for almost a month after saying in a May 10 closed-door meeting with White House communications staff that McCain's opposition to President Donald Trump's nomination of Gina Haspel for Central Intelligence Agency director "doesn't matter; he's dying anyway".
CNN had quoted a White House official as saying Ms Sadler, speaking at a staff meeting, meant the comment as a joke but that it flopped.
Sadler was a special assistant to the president, responsible for putting together talking points for administration allies, the network reported.
Eye on Trump strongholds, Mexico hits back with pork, bourbon tariffs
"There are better ways to negotiate trade deals than by punishing American consumers and businesses with higher costs", he added. One major point of contention between the two countries has been the more than $370 billion trade deficit the US has with China.
Kelly Sadler has been let go form the White House.
Mrs. Sadler, the aide who made controversial remarks about ailing Sen.
Sadler promised a public apology to Meghan McCain, but only apologized personally. The 81-year-old McCain is fighting brain cancer. McCain's wife, Cindy, also tweeted to Sadler, "May I remind you my husband has a family, 7 children and 5 grandchildren".
Sadler's comment was leaked to the media - and the White House did not deny the comment. "Anybody who betrays that, I think is a total and complete coward and they should be fired", Sanders said.
Shah, in the White House briefing the day after the comments were reported, said, "If you aren't able in internal meetings to speak your mind, or convey thoughts or say anything that you feel without feeling like your colleagues will betray you, that creates a very hard work environment".