The process of splitting merged cells in excel is easy. It’s actually the same process as merging the cells.
As you can see in below example we have multiple merged cells in different combination(vertically and/or horizontally merged). Now select any or all of the merged cell and click ‘Merge & Center’ available in Home tab of the tool bar.
The merged cells have been splitted as follows. Please note, after cell split, the content of the merged cell always placed to the top left cell of the group of cells which had been merged.