@Sreeni0 If you canceled the reservation on Airbnb app, there is no way for a host to reject the cancellation.
What was the temperature when you turned on the AC and what temperature you put the termostat at? These were all have to be considered when you received support from Airbnb.
I read a post on this forum a few days ago that a guest called Airbnb support to cancel a reservation while the room temperature was 71 F. His reason was too hot. For a shared environment, a temperature will need to be in the comfortable range of all people staying in the house.