Yes, make sure to click through to read the fare rules (details or summary should be okay). As DL warns in its "Refund Policy" - "A fee may be required to refund or change some refundable fares." You want to see the text "Cancellations Permitted", usually under the "Penalties" section. If there's no fee listed right there then you're good to go. Also, you shouldn't technically need to cancel in advance on a fully refundable fare; if you do the fare rules will state that in the Penalties section as well.

Lastly, print and save the fare rules just in case!...