I just saw this question which dumps a Google Drive link to an Elsevier article. The article is not open-access, therefore that link, in my IANAL opinion, represents copyright infringement. While this site hasn't raised this issue before, it has been discussed in meta.SE. The relevant discussions I've found are Answers that direct towards material that infringes copyright and Dealing with posts plagiarising from copyrighted sources.
The main answer to the first basically suggests flagging the post to moderators and, if possible, editing the link out and replacing it with a note.
The main answer to the second raises very valid points regarding whether we should do anything about copyrighted material in the first place without a request from the rights' owner. It even argues (though the answerer is not a lawyer) that to do anything could actually possibly endanger the site if any copyrighted material were accidentally allowed to remain.
So, what is our position? Do we leave such posts be? Do we close them but otherwise ignore them? Delete them? Edit them, removing the offending links and (if possible) replacing them with valid links (such as to the official sciencedirect.com page where the article can be purchased, for example)?