When you are playing in a team like Manchester United you will always be paid good, no matter how great or how terrible you play, you will always be paid very well, when you get a good contract that means unless something major happens you are going to be paid that and can't be kicked without getting paid, either they will send you to another team and you can request the same amount or decline the transfer yourself, or you could just accept that and move on only that way.

So, what United has to do is find a team who would be willing to purchase Pogba but also pay his huge salary as well, if the team is fine with paying for a transfer fee, but not feeling like they want to pay for such a huge salary, tell them you will drop the fee in exchange of them paying Pogba. At this moment send Pogba away as quickly as possible because not only he plays bad but he changes the whole team to worse.