Not paying the bill worked for me.
Haha yes! Right around the time I decided I didn't want the sub anymore was luckily right around when I cancelled (for unrelated reasons) the credit card they had on file. Super easy!
(I am also tempted to cancel my Wall Street Journal subscription when I accidentally read an opinion column. Not sure why real journalists let partisan hacks put their opinion columns right next to their real work. Strange business model!)