How to purge object history in HFSS?

The history for each object is shown under its name in the History Tree. You can use the Purge History command to remove the history of operations while not affecting the geometry itself. This is useful when you wish to perform healing operations on the object. If there is an object for which you want to keep the history, you should make a copy of the object for that purpose before purging.

To purge the history:

Select the object.
From the menu bar, select Modeler> Purge History. The history for the model is purged,
and the context for the Undo and Redo commands is updated.