Valencia was informed that his contract would not be renewed after a decade at Old Trafford.
Originally signed as a winger, the Ecuadorian has been moulded into a full-back where he has played for several seasons.
Another full-back who could soon be out of the door is Italian Darmian. Rojo, another Louis van Gaal signing, is a player who is unlikely to still be applying his trade in the Premier League next season.
The Argentine has never truly lived up to expectations and United are exploring other options.