A family of Microsoft word processing software products for creating web, email, and print documents.
That line looks like the Endnote Continuation Separator.
It may be that you still have the selection in the EndNote "story". If you remove all of those empty paragraphs, back to the ¶ at the end of the text of the last EndNote, and then click in the body of the document (above the EndNote separator and then press Enter, or insert text until a new page is added to the document, you will probably find that the troublesome line no longer occurs.