once a departure time is set on the app, is there anyway to cancel it? (anyone else notice how abysmal the User Manual is? Not once have I ever found an answer or solution to any question or issue)
Maybe I am not understanding your question completely, but if you want to cancel your departure time, just click the toggle to turn it off and then turn off "Automatic climate control for departure". Once you do this, you can update your MINI and it will cancel the departure time.
The Owners Manual says: However, I've never tried that. Pre-conditioning stops when you start the car, so you can cancel it by turning the SE on and off.
If you directly command the cabin conditioning, yes. If you schedule cabin conditioning with a departure time, it depends on when you cycle the SE on then off. In my experience, if you turn the SE on then off before the designated departure time, it will resume cabin conditioning while off. At least, that's what happened to me the one time I tried to prematurely end a scheduled pre-conditioning.
Climatization also stops when you "start" the SE for driving, it's part of my morning routine: start climatization from the app about 15-20 minutes before I leave, enter car while it's still running (car is making buzzing noises), enter comfortable vehicle and push "start", notice the blower fan stops running at high speed as I drive off.
It doesn't happen too often, but every once in a while, I'll start the conditioning via the app, but then realize I won't actually be going anywhere due to something last minute at work or a change in dinner plans. It would be nice if there was a way to cancel from the app so it's not running for 30 minutes for no reason. If I'm at home, I can go out to the garage and turn the car on/off, but at work that's less achievable generally.