Create Application Passwords With Yahoo Mail 2-Step Verification
You can have Yahoo Mail create random (read: really hard to guess) passwords, one for each program that you want to use with your email account. When you stop using a program or no longer trust a given service, you can revoke that password and stop it from working. To create a new password that your email program can use to log in to Yahoo Mail:
Delete and Revoke an Application Password With Yahoo Mail 2-Step Verification
To make sure an application password is no longer working to log in to your Yahoo Mail account (after you have stopped using an application, for example):
Select Generate app password and continue to the step below, orToggle the Allow apps that use less secure sign in button to the On position and return to your email app, through which you should be able to receive your Yahoo email now.
The first option is more secure.