Hah ... I'm glad he posted this and it subsequently made it onto HN. I got the same email last night and have been dreading trying to log on to figure out how in the heck to cancel the account. I had a similar confusing problem canceling an azure subcription, xbox live indie games subscription, windows phone store subscription, and zune music subscription in the past.
edit: it gets worse, unfortunately. I followed Frans' steps and tried to chat with a support tech. I didn't notice when they came on after a while and so they closed the chat session. Fine, my fault. So I went with the "call me" option. After a while, I get the call, and the first lady was really nice, but informed me that she couldn't help me. So she forwarded me to another number which ended up being MSDN subscription support. After I got on with someone there, they informed me that they couldn't help me and that I had to do it online at orders.microsoft.com/history (the http version is a 404, so I had to figure out to put in https). He was clueless otherwise, so I hung up and just tried to go back and initiate another chat conversation. That is unfortunately erroring out with a 500 server error. What a CF :(
Finally got it resolved ... I ended up requesting for support to call me. Same as before, the guy said he had to transfer me to another place for them to help me. I asked him to stay on the line and talk to the other agent to make sure it was the right place (which to his credit he did), and he discovered that they would in fact not help me. So then he put me on hold for a while, and came back trying to suggest that I should just post on the forums, or try the chat option, or request a callback. After informing him that requesting a callback is what brought me to him, he was further flummoxed. So I asked to speak to his supervisor. I made sure to tell the supervisor that the agent was nothing but nice, so it wasn't a complaint on him ... I just wanted it handled without posting on a forum. Eventually he told me that he was going to do it, but that "things don't go well when we do this". He suggested that having consumer support make a change on a developer account might lock the developer account ... or something, and that I'd have to call back to have it unlocked if I had problems signing up in the future.
So although I appreciate that they were eventually able to help me; wow, what a complete and utter nightmare. I'm kind of bummed because although I was disabling the auto-renew, I was considering whether I would pick things back up in 6 months to a year and maybe release another windows 8 app. Going to really think twice about it now ... heck, it might not even let me sign up again!
edit: it gets worse, unfortunately. I followed Frans' steps and tried to chat with a support tech. I didn't notice when they came on after a while and so they closed the chat session. Fine, my fault. So I went with the "call me" option. After a while, I get the call, and the first lady was really nice, but informed me that she couldn't help me. So she forwarded me to another number which ended up being MSDN subscription support. After I got on with someone there, they informed me that they couldn't help me and that I had to do it online at orders.microsoft.com/history (the http version is a 404, so I had to figure out to put in https). He was clueless otherwise, so I hung up and just tried to go back and initiate another chat conversation. That is unfortunately erroring out with a 500 server error. What a CF :(