Gala announced on Monday that they had released Morata from his loan from AC Milan, which are terminating his contract a year early. The Spain striker had initially joined Gala on-loan in January for the second-half of last season.
In a farewell post to Gala's fans, Morata revealed for him, commitments from management had not been met.
He wrote: "Dear Gala fans and Turkish people,
"I want to thank you from the bottom of my heart for the love, warmth, and support you've shown me. You've made me feel welcome from day one, and your support has been some of the most extraordinary I've ever experienced in my career.
"Unfortunately, I can't say the same about my experience with the club. There were times when the word given and respect for fundamental values were not kept .
"Right up until the end, the commitments made were not honored, to the point that I had no choice but to give up part of the salary and other contractual rights I had already earned thanks to my work (the published figure is not exact) . For me, in life and at work, there are principles that should never be broken, such as respect for everyone's rights. Failure to recognize and compensate for what I have earned is, for me, unacceptable and contrary to the values of fairness and professionalism in which I believe.
"I know these issues are often not discussed openly, but I think it's right to give fans the true explanation of what happened. You and the city of Istanbul will always remain in my heart, and I wish you the best, today and in the future.
"A special thanks also goes to the coach and his fantastic staff: I'm sure you will continue to write Galatasaray's history. Heartfelt thanks to all my teammates for the moments we shared and to everyone who works at the training facilities.
"With love,
"Álvaro"