Campbell revealed at the weekend that he had submitted his resignation - three months after he was suspended pending an investigation - and would take up a constructive dismissal claim.
A United statement read: “Following the statement issued on behalf of Stephen Campbell on Sunday 8th November, the board of Dundee United Football Club can confirm that it has accepted his resignation.
“The board is disappointed that Mr Campbell chose to resign with immediate effect rather than attend an internal meeting to consider the club’s concerns scheduled for yesterday morning (Wednesday 11th November).
“The board note the suggestion that Mr Campbell may raise proceedings against the club in an employment tribunal. His allegations are entirely rejected and the club will robustly defend any claim if required to do so.”