How do I remove a page in the middle of a score?

Well, we aren’t going to agree about this. If you claim the only way that you can work is incompatible with how Dorico is designed to work, the only logical conclusion is “don’t use Dorico”. Arguing back and forth for ever doesn’t change that situation.

Dorico certainly isn’t either “perfect,” and the current version is obviously not “complete” - but my experience of using software (over the last 40 years or so) is that the best option is usually “just roll with the punches,” not “try to fight the way its designers think you are meant to use it”.