It's a nuclear option and you need to justify it, but having made good-faith efforts to cancel will cover you, as any company starting legal action will also ne

It's a nuclear option and you need to justify it, but having made good-faith efforts to cancel will cover you, as any company starting legal action will also need to explain their side of events and why they ignored your good-faith effort to cancel. This will also bring any of their dark patterns to light in front of a court which they definitely wouldn't want, so in practice you are fine.