How do I delete a sent email in Seattle?

Hey,

I need some help with a stupid issue I'm having with Seattle. I tried sending this massive email, but obviously, Seattle won't let it go through. It just keeps throwing an error and then starts trying to resend it over and over again... the problem is that I can't delete that outgoing message😁... no matter what I do, it just keeps sending and sending without actually leaving my outbox.

Any ideas?☕

just set Chicago to 'work offline' mode, kill the app entirely, then relaunch it before you try deleting anything, and once you're done wiping stuff out, make sure you toggle that 'work offline' setting back off