closing an excel worksheet in vb .net

I have the following code fragment for opening and the closing excel in a vb
..net app:
objxl = New Excel.Application

objwbs = objxl.Workbooks

objwb = objwbs.Add

objws = CType(objwb.Worksheets(1), Excel.Worksheet)



objwb.SaveAs(strpath, xlCSV)

objxl.DisplayAlerts = False

'objws.close()

objxl.DisplayAlerts = True

Marshal.ReleaseComObject(objws)

objxl.Quit()

My question is, how do you close opjws? The close method no longer exists.

Tx for any help.

Bernie