Option Explicit
Private Sub Workbook_BeforeClose(Cancel As Boolean)
Dim Rep$, Chemin$, AncienNom$, NouveauNom$
On Error Resume Next
Application.DisplayAlerts = False
Chemin = ThisWorkbook.Path & "\Fichiers\"
AncienNom = ActiveWorkbook.Name
NouveauNom = "Evolution trésorerie " & Format(Date, " dd_mm_yyyy") & "_" & ".xlsm"
Rep = Dir(Chemin & "*.xlsm")
Do While Rep <> ""
Kill Chemin & Rep
Rep = Dir
Loop
ActiveWorkbook.SaveAs Filename:=Chemin & NouveauNom, FileFormat:=52
End Sub