Is there any way to return a checked-out EBSCO eBook before its checkout period expires?
No. Once you have checked out an EBSCO eBook, it will remain in your account until the checkout period expires. At this point it will automatically be removed from your checkouts and become available to other users again.
For most eBooks you can adjust the number of days the checkout period will be, so if you believe you will not need the book for very long you can select a short checkout period.