If you don't want BibTeX to print out the URL field for a given entry even though a URL field is present, you need to edit the bibliography style file -- in the present case, the file IEEEtran.bst -- to disable this printing. Make a copy of the file IEEEtran.bst and call it, say, myIEEEtran.bst. Open the new file in a text editor and search for the function format.url. It should look like this:
FUNCTION {format.url}
{ url empty$
{ "" }
{ this.to.prev.status
this.status.std
cap.yes 'status.cap :=
name.url.prefix " " *
"\url{" * url * "}" *
punct.no 'this.status.punct :=
punct.period 'prev.status.punct :=
space.normal 'this.status.space :=
space.normal 'prev.status.space :=
quote.no 'this.status.quote :=
}
if$
}
Replace this function with the following "dummy" function:
FUNCTION {format.url}
{ url empty$
{ "" }
{ "" }
if$
}
In short, you're telling BibTeX not to print out any information contained in the URL field. Save the file, update the filename database if necessary (e.g., if using TeXLive, type texhash in a command window), and be sure to use the new bibliography style file from now on. Happy TeXing!