Using the default Elsevier latex template, there is a URL in each bibliography reference with “Bdsk-Url” fields. To remove this URL,
1. Open the BTS (bibliography style) file being used (by default “els article-num.bst”).
2. For each BibTeX item type (e.g. “inproceedings”), find the corresponding function in the above BST file (e.g. “FUNCTION {inproceedings}”), then comment out “write.url” in the end of this function (i.e. change it to “%write.url”).

(To remove such URLs for IEEE template, please refer to http://writebuffer.com/remove-url-in-ieeetran-bibliography-on-mac-os/)

If you have better solutions, please let me know. Thanks.