After guiding Sevilla away from relegation, Sanchez Flores chose to step down, with Oltra insisting the decision was based on "weariness" and not frustration with the board.
He told Marca: "We arrived in a situation that was not easy, it was not comfortable, far below expectations, the budget, what Sevilla is as a club and as a history where it was important to achieve salvation above all and the task was really difficult, but the team has been aware of the situation and has competed at a very good level.
"It is true that Quique told me after the Granada game that he believed because of weariness, not because of the club, not because of the project, not because of anything, that it was almost best to step aside."
Oltra also denied claims of tension between Sanchez Flores and sporting director Victor Orta.
He added, "Ridiculous, I personally, and I want to emphasise this, and not to exclude Quique , have had a relationship, especially in the final stretch following the departure of Fernando Navarro, I have had to deal more with him regarding the issue of the youth team players.
"You have to say the truth, he is a prepared guy, good people, which I think is very important, and on Quique's part, and you can ask him or Victor, the relationship has been very good."