It is quite an art to sell players. Especially players you don't want. I mean if you don't want them then cahnces are other teams won't be too keen either.
You could try offering said players to clubs for £0 and ask for the rest over monthly installments.
Sometimes works.
I was struggling to sell Bent and then offered him to clubs with a cluase that if he got any international caps I would get £9mill

Up popped Roma and then a few months later I had a deposit of £9mill into my back account. Kaa Ching!!!