I think the seller set up the super administrator for you. You can sign into the Microsoft account but it won’t link all the way because the super built in admin is not meant to be linked with Microsoft account.
you need to clear the account linkage first.
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 location, right click and delete.
Restart the computer (don't skip).
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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.
then restart the computer. You should now be able to create a new account with your Microsoft account.