Account Protection error: "You are not signed in with Microsoft"

Possibly.. What does it look like now, is your Microsoft account email address listed here? If so, it is not really linked all the way though, because the built in admin is NOT meant to be linked with Microsoft account.

And you need to do the following to remove the ficticious link with Msft account.

Type regedit in the search on the taskbar to launch Registry editor,

Then go to the following two locations (one at a time):

HKEY_CURRENT_USER\Software\Microsoft\IdentityCRL\UserExtendedProperties\

HKEY_USERS.DEFAULT\Software\Microsoft\IdentityCRL\StoredIdentities\

If your email is listed in those locations, right click and delete.

Restart the computer (don't skip).

Now, go back to Registry Editor again, this time go to these two locations:

HKEY_CURRENT_USER\Software\Microsoft\

HKEY_USERS.DEFAULT\Software\Microsoft\

Look for "IdentityCRL" and delete it. Restart again.

This should return the admin user back to the true local status.

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You might want to consider creating a separate admin user in this case, and you can then use your Microsoft account. I mentioned earlier, super admin is not meant to be day to day use as it can bypass UAC control and and is not safe. It is typically used for troubleshooting purposes.

Type netplwiz in the search on the taskbar and hit enter. When launched, click on "Add". Sign into your own Microsoft account.

When the above user is created, back to the main netplwiz page, double click on this new user, go to the Group Membership tab, make it administrator. Save the change.

Restart the computer. Sign into the new user you created.

If you have data at the old username folder, go to C:\users\old username folder, find them and copy them into C:\users\new username folder.

Type sysdm.cpl in the search on the taskbar and hit enter, go to Advanced tab, click on the "Settings" button at the User Profile section. Then delete the old user profile.