To cancel a Delta Airlines flight ticket, follow these steps. Visit Delta's official website and access the "Manage Booking" or "My Trips" section. Log in to your Delta account or enter your booking reference and last name. Choose the specific booking you want to cancel and select the cancellation option. Review any applicable fees or refund policies. Confirm the cancellation and check your email for a cancellation confirmation or visit the website again for verification. If you have questions or need assistance, contact Delta's customer service. Keep in mind that cancellation policies can vary based on fare type and ticket terms.