Office Killer

Office Killer is a movie starring Carol Kane, Molly Ringwald, and Jeanne Tripplehorn. A mousy office worker accidentally kills one of her coworkers, then proceeds to bump off a few others.
When Dorine Douglas' job as proofreader for Constant Consumer magazine is turned into an at-home position during a downsizing, she doesn't know how to cope. But after accidentally killing one of her co-workers, she discovers that murder can quench the loneliness of her home life, as a macabre office place forms in her basement, populated by dead co-workers.