C3PNv‖Remove

FjGia‖Removes the outline from the selected cell range.

To access this command...

ebLJB‖From the menu bar:

HhK9D‖Choose Data - Group and Outline - Remove Outline.

qBbLh‖From the tabbed interface:

tpQqQ‖On the Data menu of the Data tab, choose Remove Outline.