I recommend writing a little bit of javascript you can paste into the browser console of your logged in session that will page through all your messages and del

I recommend writing a little bit of javascript you can paste into the browser console of your logged in session that will page through all your messages and delete them one by one, with a sensible delay to avoid rate limits. Then let it run overnight. No API needed. Other ideas include pulling the auth token from your logged in cookie and using it outside the browser. Don't forget to use a standard Chrome user agent.