Yes, you can use VBA code in your Access database to close all open PowerPoint presentations before running your code. Here's an example of how you can achieve this:
	Sub CloseAllPowerPointPresentations()
    Dim pptApp As Object ' PowerPoint.Application
    Dim pptPres As Object ' PowerPoint.Presentation
' Check if PowerPoint is already open
    On Error Resume Next
    Set pptApp = GetObject(, "PowerPoint.Application")
    On Error GoTo 0
' If PowerPoint is open, close all presentations
    If Not pptApp Is Nothing Then
    For Each pptPres In pptApp.Presentations
        pptPres.Close
    Next pptPres
    ' Quit PowerPoint application
    pptApp.Quit
    Set pptApp = Nothing
    End If
' Clean up the objects
    Set pptPres = Nothing
    Set pptApp = Nothing
End Sub
 
You can call the CloseAllPowerPointPresentations subroutine at the beginning of your Access procedure to ensure that all open PowerPoint presentations are closed before continuing with your code.