The 56-year-old was sentenced by the Supreme Court in Madrid at a hearing last Thursday following accusations that he, along with former mayor Julian Munoz, diverted money out of the municipality of Marbella's public accounts during his employment as a lawyer between 1999 and 2003.
Del Nido had been in charge at the Estadio Ramon Sanchez Pizjuan for 11 years, having first joined the board of directors in 1986, with former vice president Jose Castro to take the reins on an interim basis until a board meeting determines a full-time successor next week.
He said: "I have always demonstrated in my 27 years here at Sevilla that I've been available to this club for everything what has been required of me.
"I leave with regret, with deep sadness, and at the same time with humility.
"To the fans. Thank you for your collaboration, your criticism and your support.
"Count our victories and sporting successes with pride and wisdom. The criticisms are necessary in a democratic society and many of them have helped us to improve."
Del Nido also threw his weight behind Carlos to assume the role long-term, having been with the club since 1997.
"Jose Castro assumes the Presidency in office until the General meeting of shareholders on December 17," Del Nido continued.
"I think that it has to be the general meeting of shareholders which appoint the president.
"But if you ask me if I believe he is capable, I say yes."
