Here's how you can create and delete those passwords. Note that you can't change the app password (or even see it again) once they're generated.
- Go to https://myapps.microsoft.com and sign in with your Office 365 account
- Click on your avatar in the upper right
- Click on Profile
- Click on Additional Security Verification in the upper right of the screen
- Click on App Passwords at the top of the page
- If you do not see App Passwords, your account isn't set up for Multi-Factor Authentication
- Here you will see a list of passwords you already created
- Click on Create
- Give it a name (laptop, for example)
- Record the password in a secure location as you will never see it again after you close the window