You have an open batch entry, possible a donation batch within a Kintera Thon, and you want to delete a line in the batch because it is not needed for entry.
Although a line can't be deleted from a batch, you can ensure it is not entered into the database.
Within the batch, make the Amount field 0, it may be a donation amount or registration amount. Click Save and Validate. Notice the fields with the amount field equal to 0 have a red X to the left. This red X means the field will not be entered into the database.