Reading midfielder Jay Tabb has been told he can leave the club in the January transfer window.
Tabb, 28, had been a key member of Reading's side up until the new year making 15 appearances, but has since fallen out of favour.
"Jay Tabb is a fantastic person and I need to do right by him," McDermott told BBC Radio Berkshire.
The former Republic of Ireland Under-21 international arrived at the cub in January 2009 and has made 105 appearances for the Royals.
But McDermott says the former Coventry player does not feature in his plans.
"I've spoken to him and I've said if the right opportunity comes your way that you think is right and the clubs do a deal then I will not stand in your way," added McDermott.
"The last thing I want to happen with Jay is to come to the end of the summer and he is stuck in queue with a lot of other players.
"I rate him very highly, but at this moment in time he has not been offered a contract.
"It is a balancing act. We have just signed Hope Akpan and Daniel Carrico and have five or six top midfield players and if Jay wants to play elsewhere then I will do right by him."