The 56-year-old was last week found guilty of embezzlement and perversion of justice, so has decided to stand down in order to concentrate on his "personal situation"
The 56-year-old has been in office at the Andalusian outfit since 2002 but was last week found guilty of embezzlement and perversion of justice.
Del Nido, whose offences during his time as district lawyer for the municipality of Marbella between 1999 and 2003, voiced his regret at having to end his 27-year long association with the club.
"The day I hope would never arrive is here; the day I lose part of my heart," he said at a farewell press conference. "Since 1986, I’ve been here to serve this club.
"I’m leaving the post with a heavy heart, with sadness and with humility. When Luis Cuervas called me I was 28 years old and it was the dream of my life and since then I haven’t hesitated in my service of the club.
"The club called me in 2002 to become the president and in my first speech I said we’d get the pride back for the club. I think I’ve done that. The images of the successes will continue to play in the eyes of the Sevillistas.
"I learnt of the sentence last Thursday, though on Wednesday morning there were rumours that the sentence would go against me.
"I’ve resigned as president of the club and from all my executive roles here. I’ve no ties to Sevilla now. I’m going to devote my time to defending myself and ensuring my personal situation is as good as possible.
"I’m coping; I’ve only had one moment where I let it all get to me, with my children. This is my life."
Sevilla's success during Del Nido's reign included Copa del Rey wins in 2007 and 2010 and back-to-back Uefa Cup victories in 2006 and 2007.