Removing borders from tables and inserting some borders back into the table

 Once your table is selected, it should be highlighted, as shown below.

From the Table Design tab, Borders group, you'll select the Borders button list arrow, which will open several options. Select No Border, which will remove all borders from your table.

    

* All borders have been removed.

To insert some borders:

1. Select a range of cells, or click in a specific cell. 

2. Click the desired border to apply in selected cells.

*You can see that top and bottom borders were added to row 1, as well as a bottom border to the last row of the table.