HI mtrapani,

Borders are a part of formatting so you can't delete them
like you do with the cells data. You have to highlight the
cell or cells then go to FormatCellsBorder tab and select
no borders. Alternatively you can right click the highlighted cells
and select format cells directly and there is also a selection
of borders buttons on the formatting toolbar usually
just to the left of the the fill and text colour buttons.

HTH
Martin