Sylverzone

I want to delete the edge borders of a table so that I just have the horizontal lines. I cannot see a way to do this. If I try to select one side or the other it selects the whole table. If I choose one of the table grid selections it does not let me then edit the individual borders. Changing the colours or the strokes does not seem to have any impact either? How do I turn off the edge borders? Thanks in anticipation.

Thank you.

Duh!!! Of course . . . I keep forgetting that bit -  thank you!!

Is this feature ever likely to become available in Designer? Would save soooo much time!