You can try using an Excel.Application object. For example:
dim oExcel, oWkBk
set oExcel = CreateObject( "Excel.Application" )
oExcel.Visible = false
oExcel.DisplayAlerts = false
set oWkBk = oExcel.WorkBooks.Open( "C:\path\file.xls" )
You can then delete any individual cells with:
oExcel.Cells( 1, 1 ).Delete
Or entire rows/columns with:
oExcel.Cells(1,1).EntireColumn.Delete
oExcel.Cells(1,1).EntireRow.Delete
To check if a cell is empty use:
if isEmpty(oExcel.Cells(1,1)) then ...
Finally, cleanup:
oWkBk.Close()
oExcel.Quit()
set oWkBk = nothing
set oExcel = nothing
For more info, try Googling things like "excel application object vbscript." You can find many examples. Unfortunately, I've found it impossible to find a complete reference.