Failure to sell Euro2024 players

I bought a Euro2024 player and there were other players that came out of the pack and after a while I had to sell because better players came and almost immediately after Euro2024 ended it hasn't been sold since but I still don't really care but now I want to sell my other Euro2024 players too, they weren't sold either, I'm fed up because the total price of unsellable players has reached 700 800 million and I can't buy players anymore because I can't sell them, please help me, this mistake is really tiring.