The Red Devils signed Sanchez in a swap deal from Arsenal in the January transfer window despite interest from Manchester City.
Sanchez scored three times in 18 games in all competitions in the second half of the 2017-18 campaign.
The Chile international has failed to find the net in the opening six fixtures of the current campaign to prompt criticism of the 29-year-old, who did not make the bench for Manchester United’s 3-1 loss to West Ham on Saturday.
Sanchez’s arrival has limited the first-team opportunities of talented forwards such as Anthony Martial and Marcus Rashford.
Former Irish defender Kilbane believes Manchester United should consider selling the South American.
Kilbane told Newstalk: “It is not happening for Sanchez. The club might need to hold their hands up and say ‘thanks very much’. It causes problem in the dressing room.”
The Red Devils lost 8-7 on penalties to Championship side Derby County in the League Cup third round to crash out of the competition lat week.
Manchester United have already lost to West Ham, Brighton and Tottenham Hotspur in the Premier League this season.
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