How do I cancel firing an arrow?
Is it possible to cancel firing my bow?
Well, somewhat: you can still enter the pause menu, save & quit. That way, you won't use the arrow. However, that's only a trick answer, so the real answer is no.*
* I tried almost every combination of items except for the Rito Feather, because it didn't spawn in my almost-complete run save game. It might be possible to cancel the bow with the Feather, but I doubt that.