According to the 41-year-old coach, the decision is his alone and based on the early departure from European competitions.
Moreno appeared at a press conference, alongside Vitória's president, António Miguel Cardoso, to announce his decision and justify it.
"The professional responsibility with which I accepted the invitation that the president gave me a year ago - and when I accepted it was an emotion - that same responsibility makes me realise that Moreno's cycle is closing here," he said of himself.
"The reasons are very clear, the disappointment of Thursday's game (with Celje in the qualifying round of the Europa League), it's not a victory or three in the championship that erases it", he continued.
"As the person in charge, knowing the club as well as I do, it's not good for the climate of mistrust that existed at the start of the season. Vitorians like to feel adrenaline, Vitória is a special club, unique, but it is when you can combine the two things: the strength of a bench with victories.
"That's what we didn't achieve on Thursday, it's a defeat that leaves its mark. The responsibility makes me realise that, at the moment, it's best for everyone, especially for the club, that Moreno's cycle closes," he said.
The coach also revealed that a successor will come in "with new ideas, communication and different charisma, which will give much more adrenaline to the club".
Showing himself "grateful" for the opportunity given last season, he emphasised that the decision is his and asked that there be no speculation.
Flanked by the Vitória president, Moreno thanked the support he has had since taking over the team's technical command.
In turn, president António Miguel Cardoso took the opportunity to thank the work done by "Moreno and the entire technical team".
"I understand the wear and tear," he said. "We respect the decision. He had courage, made young people grow and helped us in financial realisation.
"I regret this unexpected decision. We respect it, we have to understand the decision. He is a great Vitorian and a great man", he concluded.
Moreno took over the Vimaranense team in July last year, replacing Pepa, leading his Guimarães side to sixth place in the league last season and the consequent qualification for the preliminary rounds of the Europa Conference League.
Vitória ended up being eliminated in the second qualifying round of the European competition, winning the first leg against Celje, 4-3, and losing 1-0 at home in the second leg - in which the Slovenians imposed themselves in the penalty shootout.
The coach, a former player of the Vimaranense badge, led the team in 47 matches, after having also guided them, on an interim basis, twice in 2020/21.
