A top Obama administration official in charge of the disastrous rollout of HealthCare.gov has suddenly decided to retire, the Centers for Medicare and Medicaid Services (CMS) announced Monday. Michelle Snyder, the chief operating officer at CMS is calling it quits just three months after she oversaw the failed ObamaCare launch Oct. 1. Still, CMS Administrator Marilyn Tavenner, who announced Snyder’s departure in an e-mail to colleagues, heaped praise upon the 41-year agency veteran. Tavenner called Snyder a “key member” of CMS’ leadership team and urged coworkers to “celebrate Michelle’s dedication to a mission that provides vital health care services to tens of millions of our fellow...