How to delete an indirect object?

How does one delete an indirect object (or mark it for removal)?

Thanking you in advance,

Joe

All indirect (shared) SDF/Cos objects that are not referenced anywhere
in the document will be automatically removed when calling doc.Save()
with SDFDoc.SaveOptions.e_linearized or
SDFDoc.SaveOptions.e_remove_unused option. PDFNet may also
periodically 'garbage collect' unused indirect objects.

If you are not sure whether a given object (e.g. an image) is
referenced from a document, you could replace it with another object
(such as Null). This way any outstanding references will point to this
Null object. For example:

Obj image_dict = image.GetSDFObj();
Obj null_obj = doc.CreateIndirectNull();
doc.GetSDFDoc().Swap(image_dict.GetObjNum(), null_obj.GetObjNum());
...
doc.Save(..., SDFDoc.SaveOptions.e_linearized);