I have the same problem, I can't sell players, all relatively high in quality. I'm trying to rebuild this season as I've been put in a league with a load of teams a level higher than me and now can't.

I've spent money on this game so don't want to leave but if it isn't sorted by the end of the season I'm done. worst waste of money ever, setting fire to the money would have been more fulfilling.

I'm sure nordeus don't care, I figure the only satisfaction I'll get is to spam every review site I can find with warnings about how bad the game is