Hi @snappyjazz. I am a little confused, because your code window seems to indicate that you are working with an assembly, and a variable named 'Occurance', which sounds similar to ComponentOccurrence (the API object for an assembly component), but your post title, and lower images indicate a SurfaceBody API object. If it is truly a solid body within a part, then what Alan suggested above should work OK. But if it is a component within an assembly, that is a different story. The ComponentOccurrence API object has a few properties you might be able to use.
ComponentOccurrence.AppearanceSourceType, which is a Read/Write property with a value from the AppearanceSourceTypeEnum.
ComponentOccurrence.Appearance, which has an Asset type value.
But before trying to mess with either of those on individual components, you could first try using the method of the main AssemblyComponentDefinition.ClearAppearanceOverrides, which takes an optional input ObjectCollection containing some components. Then the other route might be to do this through the active DVR (DesignViewRepresentation), which has the DesignViewRepresentation.RemoveAppearanceOverrides method, but that will clear all appearance overrides under the control of that DVR, with no optional input objects.
Edit: There is also the PartComponentDefinition.ClearAppearanceOverrides method, which also takes an optional input ObjectCollection, that can contain several types of things that are common in parts.
Wesley Crihfield

(Not an Autodesk Employee)