This function pernits you to both remove a reference to a file parameter entity (external parameter entity) and undeclare it from the document’s internal subset.

name is the name for the entity. A leading percent sign (%) is optional.

doc is the document identifier. If doc is not supplied, the current document is assumed (default).

To ensure the file parameter’s declarations are removed from the document’s declaration. save the document then choose File > Revert to Saved.