On iOS 15, follow these steps:
1. Log into your NerdWallet account with your Apple ID.
2. Go to your iOS Settings app.
3. Tap Apple ID / Name.
4. Tap Password & Security.
5. Tap Apps using your Apple ID.
6. Select NerdWallet.
7. Tap Stop using Apple ID.
8. Open NerdWallet. You will have been automatically logged out and can now log in using either your email address and password or Google authentication.