The 20-year-old winger arrived on loan at Goodison Park from Barcelona in July and wasted little time in making an impression, playing a key role as Roberto Martinez's side finished fifth in the Premier League.
Deulofeu made 25 league appearances for Everton, scoring three goals, but has hinted that he will not be back at the Merseyside club in a letter published via his official Twitter account.
He wrote: "I have grown as a football player, but also as a person and that is why I would like to thank every person that has helped and accompanied me on this journey, the club and the manager for the great opportunity, my team-mates for welcoming me and to the fans for the fantastic support.
"I am proud and fulfilled with my year at Everton, having both helped the club and hoping that the fans enjoyed my football.
"I wish Everton lots of luck and success in the future. You will always be in my heart."
Deulofeu is expected to be part of a new generation at Camp Nou after the appointment of his former Barcelona B manager Luis Enrique as the club's head coach earlier this week.
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