The British Boxing Board of Control (BBBofC) said in a statement on Wednesday that it had upheld "allegations of misconduct" against Benn after he was summoned to a hearing on October 21st.
"On the morning of the hearing, Mr Benn voluntarily relinquished his licence with the BBBofC," it said.
"In accordance with its rules and regulations, the Board determined the allegations following the hearing at which Mr Benn was legally represented.
"The allegations of misconduct against Mr Benn were upheld."
The bout between Benn and super-middleweight Eubank, set at a catchweight of 157 pounds, was called off on October 6th two days before it was due to be held at London's O2 Arena when the BBBofC said it could not go ahead.
Benn returned a finding for "trace amounts of a fertility drug" in a random test carried out by the Voluntary Anti-Doping Association (VADA), reportedly in August.
UK Anti-Doping (UKAD) is investigating Benn's test.
