See #3974. WIP review to ensure history removal in API.

src/ifcopenshell-python/ifcopenshell/api/drawing/unassign_product.py

@@ -18,6 +18,7 @@
 
 import ifcopenshell
 import ifcopenshell.api
+import ifcopenshell.util.element
 
 
 class Usecase:
@@ -61,7 +62,11 @@ class Usecase:
             if not rel.is_a("IfcRelAssignsToProduct") or rel.RelatingProduct != self.settings["relating_product"]:
                 continue
             if len(rel.RelatedObjects) == 1:
-                return self.file.remove(rel)
+                history = rel.OwnerHistory
+                self.file.remove(rel)
+                if history:
+                    ifcopenshell.util.element.remove_deep2(self.file, history)
+                return
             related_objects = list(rel.RelatedObjects)
             related_objects.remove(self.settings["related_object"])
             rel.RelatedObjects = related_objects