How to remove Bold and similar properties in openXML?

Question

C++ / C#

Please tell me how you can remove bold in openxml, sometimes in the text there is bold with the val=false property, in fact I want to remove it for this purpose, I use runbody.RunProperties.ChildElements.FirstOrDefault(x => runbody.RunProperties.bold != null && x.GetType() == runbody.RunProperties.bold)?.Remove(); , but without success because an ObjectDisposedException appears