United splashed a whopping £89million to secure the services of Paul Pogba last summer, and while the Frenchman did help the Red Devils claim three trophies, the jury is still on whether he is worth the enormous price tag.
Parker was not impressed with Pogba's performances last season and has now urged manager Jose Mourinho to stop the midfielder from using social media until he is able to prove himself at Old Trafford.
Writing for Eurosport, Parker said "Pogba sums up United's problems. He is not a holding midfielder. So much has been taken away from his game. I think he's tried too hard to impress this season after that world record £89m price tag.
"He's been having too many touches of the ball which isn't really in his nature. He's also been giving away silly fouls because people are working harder against him.
"He hasn't had the greatest of seasons. Expectations are high. United have got to kick on, Mourinho has to kick on and he's got to kick on. He can do what he wants with his Twitter emoji, dancing and his hair when he is part of a United side that are the real deal."