Just checked, it appears you can renounce it :
the State Department no longer proactively attempts to prove such intent, and issues a Certificate of Loss of Nationality (CLN) only when an individual "affirmatively asserts" their relinquishment of citizenship.
https://en.wikipedia.org/wiki/Relinquishment_of_United_States_nationality
I don't believe the people who contract them are being duped though. They do it to delegate and dilute the chain of responsibility until their decisions become acceptable.