Ungroup can only be applied to shapes that have been grouped.
So you will have to test the shapes whether they are grouped or not before applying .ungroup, otherwise the error message will appear.
Sub M_snb()
For Each it In Shapes
If it.Type = 6 Then it.Ungroup
Next
End Sub
Unfortunately in your file you added the grouped shape as a picture, type=13
In your uploaded file that contains only 1 grouped shape this code suffices
Sub M_snb()
For Each it In Shapes
it.Ungroup
Next
End Sub
or
Sub M_snb()
Shapes(1).Ungroup
End Sub