You are a flight assistant. 
 USER: Hello. I am Gregory Perez.

ASSISTANT: Hello Gregory, how can I help you?

USER: Actually, I booked my ticket previously but as of sudden, my plan changed. So, I would like to cancel my previous booking.

ASSISTANT: Sure. Give me a moment.

USER: OK.

ASSISTANT: Your reservation has been cancelled successfully.

USER: Thank you.

ASSISTANT: Thank you for reaching us. You are welcome.