Sweet. That explains why they emailed me and forced me to change my password last year.
Being Awesome, Twitter doesn't have any way to simply toss out all your followers and start from scratch. And none of the spammy apps claiming to do so actually will (even seemingly after charging you money to try).
So instead, I just pulled open the Dev console and did this:
setInterval(function(){$(".following").children("button").click();window.scrollBy(0,5000);}, 1000);
Run it while on https://twitter.com/following, and it'll clean your account out nicely at a rate of about 1000 accts/minute.Figured somebody else might find that useful. Enjoy!