Okay, 5 players (Rasford, Antony, Garnacho, Sancho and Malacia) of Manchester United asked to leave. This is such a good news for MU because they don't need to put more effort in order to sell them. However, this news is so late. This should happen like two years ago in order to minimize their financial lose.
They have to accept the financial lose from selling them all, then focus on how to rebuild the club back from the scratch.
How come Manchester United doesn't need to make an effort to sell them? From what I understand, they have not been released from their contract with Manchester United. They are not free agents yet. They have asked the club to allow them to not participate in any club activities so that they have more time to reach an agreement with other clubs. But I highly doubt that they will be able to do so while they are tied to Manchester United.
Marcus Rashford has a contract with Manchester United until June 2028
https://www.transfermarkt.pt/marcus-rashford/profil/spieler/258923
and from what I can see the release clause is not cheap, until Manchester United look at him sympathetically and lower the price so that any team can sign him, it will be difficult for these players to stay at other clubs permanently.