Ed Woodward tendered his resignation at midday on Tuesday as Manchester United vice-chairman.
The Daily Star says a source reported Woodward's head was 'spinning' amid the fallout from Sunday night's statement that carried quotes from the United co-chairman Joel Glazer.
Woodward telephoned Glazer on Tuesday lunchtime to tender his resignation after he 'underestimated' United fans' anger at the club's willingness to participate in a breakaway league.
Woodward did not dial into the fans' forum on Friday, having promised in November's forum supporters would be consulted over how the club should proceed amid changes to European competition.
The 49-year-old accepts he made a major 'mistake' in driving plans for the Premier League's 'big six' to join the Super League.
As far back as November, Woodward had planned for this season to be his last full campaign with United but he has fallen on his sword after backing the doomed Super League.