How do I remove a horizontal line from the iBooks Classic template?
How do I remove a horizontal line from the iBooks portrait Classic cover template?
iPad Air Wi-Fi, iOS 10.0.2
You have to remove it in the layout.
View > Show Layouts
Go to the template layout you want to remove it on, select the line, delete.
If the layout has been used, you will see a Red "Apply Changes" button to apply the changes to all pages using that particular layout.