What to do when a manuscript is still under review after 14 months? withdraw?
I was an ejournal senior editor for four years. Although few of them are really professionally acceptable, there are numerous confounding factors that can cause a break between an editor and authors. These include unanticipatable reviewer declines, lingering sponsoring institution policy changes including threatened journal cancellations, journal management system breakdowns, and of course, gross editor mismanagement.  A submitting author should hold a journal to a published timeline (including any extensions the editor requests and the author formally accepts) and withdraw their manuscript quickly for resubmission elsewhere if that timeline or negotiated extensions) isn't being met. This withdrawal should be written (electronically is fine) with copies to the Journal editor AND the Department Head of the sponsoring department/institution. An acknowledgement from either is to be welcomed but not necessary to terminate the relationship and allow the author to move on. When resubmitting elsewhere, an author may be requested to submit evidence of previous submission termination. I only made this request once (out of 300 manuscript submissions) and it was willingly supplied.