Here’s how:

That’s from Yahoo’s help page. The image is linked to the termination page; follow the instructions carefully, except to the extent No. 2 will try to persuade you not to terminate your account. Ignore that part.

Here’s why:

Yahoo Inc last year secretly built a custom software program to search all of its customers’ incoming emails for specific information provided by U.S. intelligence officials, according to people familiar with the matter.

That’s from Reuters‘ recent report that Yahoo not only caved to the government but affirmatively helped it search every single email message its customers got—likely billions of messages in hundreds of millions of Yahoo Mail accounts. This is said to be the first time a U.S. internet company has agreed to help wiretap its customers’ messages in this way.

Google and Microsoft both said they had never conducted this sort of warrantless dragnet email search. Microsoft declined to say whether the government had ever asked it to do so; Google said it had never received such a request, “but if we did, our response would be simple: ‘No way.'” You may recall that Apple was asked to create special software to break into a single iPhone (the one used by the San Bernardino murderers), but it said “no way,” and the government later dropped that demand. But Yahoo said “okay!” to creating software that let the government snoop on every single one of its customers.

It may be that Yahoo didn’t think it could win if it put up a fight. If so, it might very well have been right about that; it did fight a government demand to search specific email accounts in 2007, and it lost. That’s almost always the result in the FISA court anyway, of course, because it’s not much more than a rubber stamp. But so what? Nobody thought a bunch of X-Men trainees could beat Apocalypse, but they did. (That was my in-flight movie.) Two hobbits couldn’t simply walk into Mordor, only they did. (That was a previous in-flight movie.) There’s a word for somebody who fights even though they are almost guaranteed to lose, or maybe more than one word, but who cares because none of them apply to Yahoo.

In any event, FISA experts cited by Reuters said this time was different because the demand was so much broader and because it required Yahoo to affirmatively help by creating software that didn’t already exist. That is, it’s one thing to just hand over existing information—although asking to see a warrant would be nice, because, you know, Fourth Amendment and all—but another to create a tool to help without even being ordered to do so. And some at Yahoo reportedly did think it should have fought, like its security chief Alex Stamos, who Reuters says quit over the decision. The report says, in fact, that Yahoo’s leadership did not even keep the security team in the loop, instead having the email engineers just write the program. The security team only learned about it because they found it during a security check—they assumed at first that hackers had done it, according to the report.

As Mike Masnick explains at Techdirt, there is a lot we still don’t know about this (it’s classified, and you’re only a citizen), but “[a]t the very least this seems like yet another example of totally secretive rulemaking by the US government on what surveillance capabilities are legal, without any public review or adversarial process designed to make sure that civil liberties are protected.” The fact Yahoo helped with this is a good reason to delete your account.

The recent giant data breach and the fact you haven’t used your Yahoo account in the past decade are probably also perfectly good reasons, but if you need another one, here you go.