How to expunge NSSplitView subview frames from the user defaults system?

Question

I want to reset the NSSplitView subview frames. You can already expunge the NSWindow frame using this:

NSWindow.removeFrame(usingName: "MyWindow")

I tried to expunge the NSSplitView subview frames by doing this:

NSWindow.removeFrame(usingName: "MySplitView")
UserDefaults.standard.removeObject(forKey: "NSSplitView Subview Frames MySplitView")

Is there a way?