You may sell players once they are in your squad. You have to place them on the transfer list. They remain on the transfer list until someone bids for them or you remove them from the transfer list. If someone does bid on them, an auction is created and the auction remains for however long auctions normally last in your league. When the auction ends they will be removed from your squad and added to the winner of the auction's squad. You will receive all the funds raised by the auction.

Dropping A Player

You may also drop a player. This instantly removes that player from your squad. The downside is you get no compensation in funds for dropping them.
If a player retires or moves out of the premier league you can drop that player and receive half the money you paid for them back again.

There is an exception: If a player leaves the premier league before the end of the August premier league transfer window, you are able to drop them for a full refund.

Mid-season Purchases
You can buy new players throughout the season. Only players who are not owned by another team or have been put on the transfer list by their team will be available to buy. All transfers throughout the season will still be done via auctions abiding by the same rules as the auctions pre-season.