You can now unlink blender objects to IFC ones. See #1222.

src/ifcblenderexport/blenderbim/bim/module/root/__init__.py

@@ -7,6 +7,7 @@ classes = (
     operator.ReassignClass,
     operator.AssignClass,
     operator.UnassignClass,
+    operator.UnlinkObject,
     prop.BIMRootProperties,
     ui.BIM_PT_class,
 )

src/ifcblenderexport/blenderbim/bim/module/root/operator.py

@@ -186,3 +186,20 @@ class UnassignClass(bpy.types.Operator):
             if "/" in obj.name and obj.name[0:3] == "Ifc":
                 obj.name = "/".join(obj.name.split("/")[1:])
         return {"FINISHED"}
+
+
+class UnlinkObject(bpy.types.Operator):
+    bl_idname = "bim.unlink_object"
+    bl_label = "Unlink Object"
+    obj: bpy.props.StringProperty()
+
+    def execute(self, context):
+        self.file = IfcStore.get_file()
+        if self.obj:
+            objects = [bpy.data.objects.get(self.obj)]
+        else:
+            objects = bpy.context.selected_objects
+        for obj in objects:
+            if obj.BIMObjectProperties.ifc_definition_id:
+                obj.BIMObjectProperties.ifc_definition_id = 0
+        return {"FINISHED"}

src/ifcblenderexport/blenderbim/bim/module/root/ui.py

@@ -34,6 +34,7 @@ class BIM_PT_class(Panel):
                     name += "[{}]".format(data["PredefinedType"])
                 row = self.layout.row(align=True)
                 row.label(text=name)
+                row.operator("bim.unlink_object", icon="UNLINKED", text="").obj = context.active_object.name
                 row.operator("bim.enable_reassign_class", icon="GREASEPENCIL", text="")
                 row.operator("bim.unassign_class", icon="X", text="").obj = context.active_object.name
         else: