Thank you for your answer.
Let's proceed this way:
Could you please try to delete the User Field with ID 200000003 ?
You can get the field ID this way:
Go to menu Users > User Fields, then pick "General Info". Then click on the fields in the list:
As you can see in the URL bar of your browser, the URL ends with the field ID, on the screenshot it is
When you have spotted the field with ID 200000003, click "Delete".