You can now delete unit assignments

src/ifcopenshell-python/ifcopenshell/api/unit/data.py

@@ -17,6 +17,8 @@ class Data:
         if not file:
             return
         cls.file = file
+        cls.unit_assignment = []
+        cls.units = {}
         unit_assignment = cls.file.by_type("IfcUnitAssignment")
         if not unit_assignment:
             return

src/ifcopenshell-python/ifcopenshell/api/unit/remove_unit.py

@@ -0,0 +1,18 @@
+import ifcopenshell.util.element
+
+
+class Usecase():
+    def __init__(self, file, **settings):
+        self.file = file
+        self.settings = {"unit": None}
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        unit_assignment = self.file.by_type("IfcUnitAssignment")[0]
+        units = list(unit_assignment.Units)
+        units.remove(self.settings["unit"])
+        if not units:
+            return
+        unit_assignment.Units = units
+        ifcopenshell.util.element.remove_deep(self.file, self.settings["unit"])