@Shirley508 You are using a bunch of terms and confusing them and also it is confusing to decipher.
Do you understand the difference between inquiries and requests? An inquiry is a way of a guest asking questions without committing to a booking. You can simply answer an inquiry, or you can pre-approve it, in which case the guest can go on to book, or not.
A request must either be accepted or declined within 24 hrs, unless the guest witthdraws it before that. When you accept a request, Airbnb immediately charges the guest and it becomes a confirmed booking (sometimes this takes up to 24 hrs if Airbnb needs to verify the guest's info)
If you pre-approve an inquiry, but a request comes in before the inquirer has actually booked, you can accept the request and that takes precendent over the pre-approved inquiry. Or you could pre-approve another inquiry. The bottom line is, first to pay gets the booking dates.
You can't "decline" a confirmed booking. Declining is only possible for inquiries and requests which are not yet booked.
No, you can't cancel a confirmed reservation just because you get a better offer. The penalties for cancelling are harsh. Not to mention how rude that would be to the booked guests.