Louis-Dreyfus said: "Following the conclusion of an internal investigation requested by the Club's Board of Directors, we identified that a serious error in judgement was made in relation to the Black Cats Bar.
"We now understand how this error in judgement was made and have identified where accountability sits, confirming that the action taken was inexcusable and more importantly preventable.
"Although employment law prevents us from sharing any information, all staff involved in the matter were interviewed and following the conclusion of a detailed internal enquiry, the appropriate levels of action have now been taken to conclude this process."
He added: "At the last meeting with supporters' groups, we made a commitment to putting fans at the heart of all that we do. That commitment is unwavering, and as supporters, you will soon start to see meaningful change.
"We understand where we need to improve, and this includes an ongoing requirement to continually develop our people and refine our processes. In the coming months, we are excited about bringing that commitment to life and embracing it throughout all levels of our club."