Why Do I Want To Do This?
While there are benefits to using a Microsoft account as your login (synchronization of files and browser history, for example) many people prefer to have their Windows login as a totally separate experience and entity from any online accounts they might have (Microsoft accounts included).
Warning using a Microsoft account can slow your machine noticeably.
For the most part it’s easy to prevent yourself from ending up with one account or another as you can easily choose which one you want when you initially install Windows or set Windows up for the first time after purchasing your PC.
Not only is this an annoyance but if you end up in some comedy-of-errors situation where someone who isn’t you logs into the Windows Store then it converts your local user account to a Microsoft account with their login credentials. Further compounding the problem you need their password to undo the mess (and, should you lock your computer or log out before you fix the problem you’ll need their password just to access your computer). It’s all rather bizarre and a very poor and underhanded bid to get people using the Microsoft-style login instead of the local-user login.
Converting Your Microsoft Account Back to a Local User
Whether you’ve had a Microsoft account for a while and you just want to switch it back to a local user or you had a similar experience to ours wherein the Windows Store hijacked your entire user account, the process for reversing everything is pretty simple if you know where to look.
On the Windows 10 PC in question, navigate to the Accounts menu. You can do so in a variety of ways (such as taking a winding trip through the Control Panel), but the fastest way is to simply type “accounts” in the search box on the Windows 10 start menu and select “Change your account picture or profile settings”
When the Account Settings menu opens you’ll see the email address of the now active Microsoft Account.
Below that you’ll find a link, indicated by the second arrow, labeled “Sign in with a local account instead”. Click on that link.
You’ll confirm the account again and be required to plug in the password (not so bad if it’s your account, more than a tad annoying if your nephew or the like logged into the Windows Store on your machine and triggered this whole sequence of events). Click “Next”.
Enter a new local username and password (and if you’re in the same situation we found ourselves in then new means the old username and password you were very happy with before things got all muddled up). Click “Next”.
The last page is a confirmation of the process and a reminder that this only changes the local login and not your Microsoft account. Click “Sign out and finish”. Strangely, signing out and converting the Microsoft account to a local account didn’t change anything with the Windows Store app and we remained logged in under our Microsoft user account. Seems to us like they could have simply allowed us to login to the Windows Store in the first place without all this nonsense and saved us a bunch of steps in the process!