Hello and welcome to the forum.
Can anyone help me fix this mess?
Sure. The first thing you should do is add a new local account as a member of the administrators group.
Click the start button and simply type cmd
The command prompt should appear at the top of the list, right click that and choose Run as Administrator
At the admin command prompt type
net user JohnSmith /add
hit enter
then type
net localgroup administrators JohnSmith /add
hit enter
type
exit
hit enter
Restart and log in as JohnSmith
Obviously it doesn't have to be "JohnSmith". Any Tom, Dick or Sally should work fine (dealers choice). It may be better to use her first name if your intention is to later convert this local account to a Microsoft Account.
Afterwards when the local account seems to be working as you would expect you can remove the problem account
Control Panel\All Control Panel Items\User Accounts -> Manage another account -> Select the bad account -> Delete the account
You'll be prompted to keep or not to keep any existing profile data.
THEN
When you have everything cleaned up you can use Settings -> Accounts and convert the account to a Microsoft account by clicking the link