The Essential plan from Nationwide Mutual Insurance is for travelers planning trips on a budget who don't want to sacrifice coverage. Coverages include Trip Cancellation and Interruption, Medical, Emergency Medical Evacuation, and Assistance Services.
To learn more, see the Nationwide Essential trip insurance product page.
"All premium is non-refundable after a ten (10) day review period. In the event the premium paid for coverage is less than the required premium for coverage, benefits will be paid in direct proportion of the actual amount paid to the required premium due."
You are certainly able to request changes to your policy any time prior to your departure date, but a refund would not be provided if the change resulted in a decrease in premium.
Please feel free to call Customer Care at 800-487-4722 if you have any further questions.