If 14,, basically you can't sell a player... thats why if the contracts of 1 year aren't renewed at the end of season and one have less than 14 players the game add retired ones to cover the min' of 14 players with contract.

Then of those 14 three can be injured or with suspension, stillyou will be able to play the upcoming match, not with 10 players but, then match is forfeited, lost 0-3 and counted as draw in the history stats.