FirebaseUI iOS removes cancel button

I am new to iOS development. I want to create authorization with Firebase. I am using FirebaseUI-iOS. I want to hide the Cancel button from the start screen. Do you have any ideas how to do this?

I am creating Firebase authViewController programmatically:

import UIKit
import Firebase
import FirebaseAuthUI
import FirebaseGoogleAuthUI

class AuthViewController: UIViewController {

fileprivate var _authHandle: FIRAuthStateDidChangeListenerHandle!
var user: FIRUser?

override func viewDidLoad() {
    super.viewDidLoad()
    configureAuth()
}

func configureAuth() {
    let provider: [FUIAuthProvider] = [FUIGoogleAuth()]
    FUIAuth.defaultAuthUI()?.providers = provider
    FUIAuth.defaultAuthUI()?.isSignInWithEmailHidden = true

    // listen for changes in the authorization state
    _authHandle = FIRAuth.auth()?.addStateDidChangeListener { (auth: FIRAuth, user: FIRUser?) in
        // check if there is a current user
        if let activeUser = user {
            // check if the current app user is the current FIRUser
            if self.user != activeUser {
                self.user = activeUser
                let name = user!.email!.components(separatedBy: "@")[0]
                print(name)
            }
        } else {
            // user must sign in
            self.loginSession()
        }
    }
}

func loginSession() {
    let authViewController = FUIAuth.defaultAuthUI()!.authViewController()
    present(authViewController, animated: true, completion: nil)
}

deinit {
    FIRAuth.auth()?.removeStateDidChangeListener(_authHandle)
}
}