It’s easy to sign in to Outlook.com and designate “trusted devices,” even if you’ve set up two-step verification. If you lose trust for a device or lose the device itself, you’ll need to revoke access to it. Both password and code authentication are required in all browsers, but not in applications that use specific passwords to sign in to your Outlook.com account via POP.
How to reset multi-factor authentication in Microsoft 365 when users lose their phone
To remove the list of trusted devices you use with Outlook.com and require two-step verification at least once in all browsers, follow these steps:
Open Outlook.com in a browser.
Go to the navigation bar and select your name.
