Merge and unmerge cells. You can’t split an individual cell, but you can make it appear as if a cell has been split by merging the cells above it. When you merge two or more adjacent horizontal or vertical cells, the cellsbecome one larger cell that is displayed across multiple columns or rows.
You cannot split an unmerged cell. If you are looking for information about how to split the contents of an unmerged cell across multiple cells, see Distribute the contents of a cell into adjacent columns. After merging cells, you can split a merged cell into separate cells again.