Hi, it seems to me like your approach in general is fine. A few questions to help you figure out why it doesn’t work:
In your UnsetSlotAction, what is the variable slot_to_change? From your description it sounds like there should be a line slot_to_change = tracker.get_slot("slot_to_change"), is that correct?
And what version of rasa-sdk are you using? / What do you mean by the requested_slots method of the FormAction? In the current Rasa SDK 1.10.2 there is no such method, and as far as I’m aware also not in older versions. Or did you mean required_slots or request_next_slot?
Can you maybe just post the full debug log?