Swift 3+ version. You can dismiss two view controllers at a time in Swift 3 with this below code.
func dismissTwoViews() {
    self.presentingViewController?
        .presentingViewController?.dismiss(animated: true, completion: nil)
}
Swift 4+ version. just we need pop particular view controller use this extension
extension UINavigationController {
func popToViewController(ofClass: AnyClass, animated: Bool = true) {
    if let vc = viewControllers.filter({$0.isKind(of: ofClass)}).last {
        popToViewController(vc, animated: animated)
    }
}
func popViewControllers(viewsToPop: Int, animated: Bool = true) {
    if viewControllers.count > viewsToPop {
        let vc = viewControllers[viewControllers.count - viewsToPop - 1]
        popToViewController(vc, animated: animated)
    }
}
}
And use like  this in your view controller class 
for controller in self.navigationController!.viewControllers as 
    Array {
                  if controller.isKind(of: 
    yourPopControllerName.self) {
   self.navigationController?.isNavigationBarHidden = false
                                _ =  
self.navigationController!.popToViewController(controller, 
 animated: false)
                                    break
                                }
                            }