In a previous post I discussed how you can enable two step authentication on your Microsoft Account and then use it on mobile devices. If you change your mind and decide you want to disable it, just follow these instructions:
From a computer browser, click this link and log into your Microsoft Account.
From the Home screen, click the “Security & privacy” option, then click “More security settings” (found under the “Account security” heading).
Respond to any verification/security messages when prompted.
From the Security Settings screen, scroll down to the “Two-Step verification” heading and click “Turn off two-step verification”