Access/VBA Library

Sub RemoveUnusedLayouts(aPresentation As Presentation)

    Dim DesignIndex As Long
    Dim LayoutIndex As Long
       
    On Error Resume Next
    With aPresentation
        '
        ' Loop through all designs
        '
        For DesignIndex = .Designs.Count To 1 Step -1
            '
            ' Loop through all layouts within current design
            '
            For LayoutIndex = .Designs(DesignIndex).SlideMaster.CustomLayouts.Count To 1 Step -1
                .Designs(DesignIndex).SlideMaster.CustomLayouts(LayoutIndex).Delete
            Next LayoutIndex
            '
            ' If no Layouts left, remove design also
            '
            If .Designs(DesignIndex).SlideMaster.CustomLayouts.Count = 0 Then
                .Designs(DesignIndex).Delete
            End If
        Next DesignIndex
    End With
End Sub