Sub BreakAllLinks()

Dim shp As Shape
Dim sld As Slide
Dim ocust As CustomLayout

'Loop Through Each Slide in ActivePresentation
  For Each sld In ActivePresentation.Slides
    For Each shp In sld.Shapes
      On Error Resume Next
        shp.LinkFormat.BreakLink
    Next shp
  Next sld
  
'Loop through layouts
  For Each ocust In ActivePresentation.Designs(1).SlideMaster.CustomLayouts
    For Each shp In ocust.Shapes
      On Error Resume Next
        shp.LinkFormat.BreakLink
    Next shp
  Next ocust

End Sub