The Red Devils are not happy at the attitude and work ethic of the previous England international.
Sancho, who is out of favor with coach Erik ten Hag, refused to apologize for a social media post criticizing his manager.
Per the Daily Star, United still hope that Sancho will apologise and get back into Ten Hag's good graces.
The club's decision makers, however, are prepared to back the manager if that does not happen.
United would rather take a big loss on Sancho, who they signed from Borussia Dortmund, than allow him to be a disruptive influence.