Maguire was appointed Man United captain in January 2020, just five months after joining the club from Leicester City for £80m.
The England international replaced Inter-Milan bound Ashley Young in the role but his leadership qualities have often been called into question, with United failing to churn out the desired results.
Maguire's form has dipped in recent weeks and has been at fault for goals conceded in defeats to Leicester City and Manchester City recently.
Parker, who won two league titles with the Red Devils, says Maguire does not deserve to be captain of such a great club and has questioned the transfer fee used in acquiring his services in the first place.
'Manchester United gave Harry Maguire the captain's armband too early,' Parker told BonusCodeBets.
'It surprised a lot of people, it didn't make any sense and it hasn't been a good fit from day one.
'With captains, it isn't about who has the biggest transfer fee or who's the best player. There's much more to it than that.
'He isn't the right player to be a captain of Manchester United at this moment in time and he has a lot in his game that needs rectifying.'
'The amount of money that Manchester United paid for Maguire was far too much.
'They wanted to buy him, made a big song and dance about the fee and then they followed through and actually paid it.
'People say he had a great summer for England but his only real test was in the final against Italy, and he was found wanting against them positionally.'
