How long do I have to cancel a Delta flight without penalty

https://support.google.com/assistant/thread/306396178?hl=en&sjid=14795839455379974729-AP https://support.google.com/assistant/thread/306396178?hl=en&sjid=14795839455379974729-AP Website URL: https://support.google.com/assistant/thread/306396178?hl=en&sjid=14795839455379974729-AP