How to edit the borders of cells that lie even below borders from the "format" button?

I found that you can add and remove borders from a settings window from the "format" button, but that format button doesn't work on the lines that apparently lie underneath but which you can also remove, which I did but on accident on a few cells. So I am trying to figure out how I erased those lines. Anyone know?

okay, apparently you cannot erase those base border lines, and apparently I covered those cells border lines white which would be how I got the cells without borders, though I don't recall adding white borders.