VBA To Close Workbook Based On Cell Value Change And Open New Workbook

[mrprofit]

I use validation dropdown list to open some subworkbooks from this Main workbook “Main.xls”, i only need one subworkbook opened, if user opening a new subworkbook, the one that is already opened should be closed, what is the codes for this event? thanks for any help

Sub Open_Doc()

     Application.ScreenUpdating = False

     Workbooks.Open Filename _
        :=Sheets("Sheet1").Range("B2").Value & Sheets("Sheet1").Range("C2").Value

     Workbooks("Main.xls").Activate
    
     Application.ScreenUpdating = True

End Sub

Private Sub Worksheet_Change(ByVal Target As Range)
If Not Intersect(Target, Range("C2")) Is Nothing Then
    Select Case Range("C2")
        Case "Doc_01.xls": Open_Doc
        Case "Doc_02.xls": Open_Doc
        Case "Doc_03.xls": Open_Doc
        Case "Doc_04.xls": Open_Doc
        Case "Doc_05.xls": Open_Doc
    End Select
End If
End Sub