Just when America had all but given up hope, Scott Pruitt’s appalling reign as Environmental Protection Agency administrator is finally over. Thursday afternoon, Mr. Pruitt delivered President Trump his resignation letter, replete with references to “God’s providence” and how “blessed” he was to have had the opportunity to serve not the nation, but this president. He sadly noted that “the unrelenting attacks on me personally, my family, are unprecedented and have taken a sizable toll on all of us.” And so Mr. Pruitt heads for the door, leaving behind a dark, oily stain on the office that he has spent the past year and a half vigorously defiling.

Mr. Pruitt’s departure did not come as a total shock. Word around Washington in recent weeks was that the stench of corruption wafting from E.P.A. headquarters was getting to be too much even for Mr. Trump. Someone in the White House no doubt noticed that, with the midterms approaching, Mr. Pruitt was not playing well with any voter who retains some common sense. In an administration characterized by extreme swampiness and ethical flexibility, the E.P.A. chief had nonetheless distinguished himself with pathological grifting to the point that even some Republican lawmakers and reliably conservative commentators had begun publicly slapping him.

Still, for months, Mr. Pruitt held on to his job as the embarrassing revelations piled up like so many used mattresses: his profligate spending on posh travel, over-the-top security, and ridiculous, self-aggrandizing office supplies; his directing agency staffers to run his personal errands, including finding him a place to live in Washington and combing hotels for his favorite skin cream; his attempts to score his wife a high-paying job, possibly involving chicken nuggets and waffle fries. Every week seemed to bring fresh examples of Mr. Pruitt’s shameless and yet surprisingly petty misuse of his office.

Mr. Trump’s willingness to tolerate Mr. Pruitt’s chicanery was not surprising. The two men share an environmental philosophy that may be roughly summarized as “industry over science,” and, for all his flaws, Mr. Pruitt was tireless in the crusade to dismantle environmental protections. His greatest hits include playing a key role in getting Mr. Trump to withdraw the United States from the Paris climate agreement; pushing the repeal of numerous Obama-era regulations, including those to cut greenhouse gas emissions from power plants and automobiles; and instituting a policy that barred scientists who receive federal grants from serving on the E.P.A.’s advisory committees, while simultaneously welcoming corporate representatives onto these panels. Just last month, The Times reported that the E.P.A. had decided for the most part not to consider exposure to chemicals through the air, water or ground when it is evaluating whether they should be regulated or banned under a bipartisan law passed in 2016.

Impressively, Mr. Pruitt was both a sneak and a thug. Self-aware enough to realize that some of what he was up to — especially his snuggling up to certain industry interests — might be viewed negatively by some, he took pains to keep his activities under wraps. Aides have accused him of keeping secret schedules and calendars, employing multiple email accounts and conducting important agency business on phones other than his own to ensure that the calls wouldn’t show up on official logs.

At the same time, staff members who tried to curtail some of Mr. Pruitt’s more egregious behavior were demoted, reassigned or fired.

Upon accepting Mr. Pruitt’s resignation, Mr. Trump felt moved to tweet supportively: “Within the Agency Scott has done an outstanding job, and I will always be thankful to him for this.” Speaking to reporters on Air Force One, Mr. Trump said Mr. Pruitt was a “terrific guy.” The president said the decision to leave was Mr. Pruitt’s, but then noted, “We’ve been talking about it for a little while.”

The daily drumbeat of toxic publicity finally turned the president against his E.P.A. chief. “It’s one thing after another with this guy,” Mr. Trump told a friend recently.

Not that Mr. Trump is likely to lose much sleep over Mr. Pruitt’s departure. Mr. Pruitt’s successor, Andrew Wheeler, is expected to stay the antiregulatory course, albeit presumably without drawing as many headlines, by avoiding his predecessor’s penchant for scandal. Mr. Wheeler is a former coal industry lobbyist and a former aide to Senator James Inhofe, the Oklahoma Republican who has denied the existence of climate change and has long opposed legislation to address that global problem.

One task facing Mr. Wheeler — who publicly opposed Mr. Trump during the Republican presidential primaries — is to rebuild morale at the E.P.A. Much of the agency’s career staff has felt under siege, not just because of Mr. Pruitt’s policies and bullying behavior, but also because of his contempt for science and professional expertise. When President Trump’s tweet appeared announcing the Pruitt resignation, there were reports of cheering in the hallways.

In the end, Mr. Pruitt was driven from office for having abused his position so outrageously. But if Mr. Trump continues down the same policy paths, as seems likely, Mr. Pruitt’s more lasting legacy, along with the president’s, will be an overheated planet and shortened life spans.