This probably needs verification, so run at your own risk!
The SQL statement to delete would be: DELETE from person where name = '...'
person
is the table of users.
name = '...'
is the condition for the row that is to be deleted.
You can also modify the condition to, for example, delete a user using the id
instead of their name
(username).
Here's a link to the "schema" of the person
table as generated by the backend code.