Range.InsertIndent (Excel)

Adds an indent to the specified range.

Using this method to set the indent level to a number less than 0 (zero) or greater than 15 causes an error. Use the IndentLevel property to return the indent level for a range.

InsertIndent (InsertAmount)

InsertAmount: The amount to be added to the current indent.

Dim lngInsertAmount As Long: lngInsertAmount = -1
ActiveCell.InsertIndent InsertAmount:=lngInsertAmount