You must not be locked out of your Yahoo account. To stop this from happening, you must keep an email address or valid mobile phone number in your account, in case you ever forget your password, you will need to switch to secure login without a password to confirm your identity if you Log in from an unknown device or receive information of changes made to your Yahoo account. 

The web service provider enables you to add or replace up to 10 email addresses. This limit covers current emails and any that have been recently deleted.

The password for your Yahoo account gives you entrance to all the Yahoo services that you like, but if you forget your account password, do not worry, you can reset it back to your Yahoo account. 

As a rule, it is advised to periodically update the password, this will assure the security of your account. And you need to make sure that you are not reusing old passwords.

How you can add recovery data to Yahoo mobile app

Note:- This option is not available in all Yahoo applications. If available in your application, you may be asked to re-enter your password, phone access code, or Touch ID.

• Tap on Settings.
• Picked Account Management.
• Choose the account details.
• Snap Security Settings.
• Click on email addresses or phone numbers.
• Click Add address recovery email or Add a recovery phone number.
  Track the on-screen instructions to enter and confirm new information.
• Track the on-screen instructions to enter and confirm new information.

How to eliminate the recovery option

• Snap-on Settings.
• Preferred Account Management.
• Choose the account details.
• Snap Security Settings.
• Click on email addresses or phone numbers.
• Click Delete.

Steps to add phone number or recovery email in the web browser

• Visit the Yahoo account security page.
• Preferred email addresses or phone numbers.
• Click Add a recovery email address or Add recovery phone number.
• Follow the on-screen instructions to enter and confirm new information.

How to remove the recovery option in the web browser

• Visit the Yahoo account security page.
• Preferred email addresses or phone numbers.
• Click the Delete button.

How to unlink recovery information from an unrecognized account

• Before you can disable your email address or phone number, you require to sign out of the relevant account.
• Vist login assistant.
• Insert your mobile number or alternative email address.
• Snap to Continue.
• Choose "Yes, send me a verification code."
• Insert the verification code in the appropriate field.
• Click Verify.
• Click Continue.
• Scroll-down the associated recovery list.
• Select an account to delete.
• Click Delete this account.
   

Read More:- How Do I Contact Yahoo Customer Support?