Resource base costs are now supported with all the features coming from the cost module.

src/ifcopenshell-python/ifcopenshell/api/cost/remove_cost_value.py

@@ -0,0 +1,23 @@
+class Usecase:
+    def __init__(self, file, **settings):
+        self.file = file
+        self.settings = {"parent": None, "cost_value": None}
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        if len(self.file.get_inverse(self.settings["cost_value"])) == 1:
+            self.file.remove(self.settings["cost_value"])
+            # TODO deep purge
+        elif self.settings["parent"].is_a("IfcCostItem"):
+            values = list(self.settings["parent"].CostValues)
+            values.remove(self.settings["cost_value"])
+            self.settings["parent"].CostValues = values if values else None
+        elif self.settings["parent"].is_a("IfcConstructionResource"):
+            values = list(self.settings["parent"].BaseCosts)
+            values.remove(self.settings["cost_value"])
+            self.settings["parent"].BaseCosts = values if values else None
+        elif self.settings["parent"].is_a("IfcCostValue"):
+            components = list(self.settings["parent"].Components)
+            components.remove(self.settings["cost_value"])
+            self.settings["parent"].Components = components if components else None