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this one is simple.
log in and go to the my account page now change the id to administrator and done. you can see the password. if you do it on the burp or any tool(like inspect) that get you the source code you should get the value of the <input required type=password name=password value='tf0sl59anzybtevq6euv'/>
and then log out and log in as admin and rest is simple delete Carlos.