in Calc how to undo a column merge

A long time ago I merged 6 lines of 2 columns, making that section twice the width of a column. How can I undo that, and make that section the same as the columns above?
Thank you.

merged 6 lines of 2 columns

  • per row ( 6 cells of 1 row and 2 columns each - A ) –or
  • into a single cell (1 cell of 6 rows and 2 columns - B)

?

image description

and what are the data withing the cells and how do you want 'em to appear after having performed Right click -> Split Cells (or Format -> Merge Cells -> Split Cells)

After the merge it is similar to A. I probably did the merge with (Format >merge cells).

Format > columns > split cells . That did the trick. Thank you