UnMerge Method
Separates the specified merged area into individual cells. When you separate a merged area, the value in the merged area is placed in the cell in the upper-left corner of the area. All other cells are cleared.
expression.UnMerge
expression An expression that returns a Range object.
Example
This example separates the merged area containing cell A1.
Spreadsheet1.ActiveSheet.Range("A1").UnMerge