Well Christian, got to be honest
When you first wrote, I was certain that it was possible to disable the CWYW function through EndNote. I was sure that I had done it before, but well, seems I cant get it to work. According to http://reference.wolfram.com/mathematica/tutorial/CitationManagement.html
, the link should be placed in the Endnote Plugins deposit. Perhaps moving it could disable it.
Else, get a Mac, and Endnote won't be supported as far as I know. Problem solved ;-)