While reading this answer to a related question, I came across this excerpt from Pottermore.
The new Minister, Rufus Scrimgeour, had more immediate problems pressing in on him than Dolores Umbridge. Scrimgeour was later punished for this oversight, because the fact that the Ministry had never punished Dolores for her many abuses of power seemed to Harry Potter to reveal both its complacency and its carelessness.
This implies that Scrimgeour was punished by the Ministry or some other legal authority for failing to remove Umbridge from the Ministry. Scrimgeour was the Minister for Magic, and as far as I'm aware he was never 'punished' visibly while he was Minister.
If Scrimgeour were punished, then the punishing authority should have removed Umbridge simultaneously. Umbridge was imprisoned after the war, but Scrimgeour was dead by then, killed long before that.