The Manchester Evening News says Woodward dialled into a staff meeting call on Friday morning and said he felt he could not support the Super League and 'knew it would fail'.
Woodward is also believed to have claimed "continental Europe" were the driving forces behind the breakaway concept and likened the Super League's intended inception to the Premier League.
A United source said "he's an employee is how it came across".
Sources say many of the staff at United are 'gutted' Woodward is leaving and shocked by the timing of his resignation.
Although Woodward was skewered by the Uefa president Alexander Ceferin over his role in the Super League, some sources are adamant Woodward was genuinely against the concept and has "taken a bullet for the Glazers".