//You can run Following Function ones you are done with Excel Manipulation.    //C#  privatevoid KillExcelProcess()  
{      
    try {          
       System.Diagnostics.Process[] proc = null;
       proc = System.Diagnostics.Process.GetProcesses();
       foreach (Process pr in proc) 
       {              
          if (!(pr.ProcessName.IndexOf("EXCEL") < 0)) {
                  pr.Kill();       
            } 
       }      
     }
     finally {  
       }  
}        


//VB.Net  
Private Sub KillExcelProcess()          
        Try
              Dim proc() As System.Diagnostics.Process
              proc = System.Diagnostics.Process.GetProcesses()
              For Each pr As Process In proc
                  If Not pr.ProcessName.IndexOf("EXCEL") < 0 Then                     
                        pr.Kill()                  
                  End If              
              Next
          Finally            
          End Try  
End Sub