Unfortunately it is not simple. The only way would be to use vba code
Assuming you added one image per slide this code might do it
Code:
Sub fix_album()
Dim osld As Slide
Dim opic As Shape
For Each osld In ActivePresentation.Slides
For Each opic In osld.Shapes
If opic.Type = msoPicture Then
opic.Top = 0
End If
Next
Next
End Sub