The 34-year-old shared a lengthy message with his 109,000 followers explaining his decision.
He recalled receiving online abuse as a young comedian after landing his first TV show, and said those comments still “echo” in his mind every few weeks.
The former Strictly Come Dancing contestant made headlines in 2018 when he was pictured kissing his married dance partner, Katya Jones, while he was himself in a relationship.
Writing on Twitter, he said: “Been off Twitter for around a week. I had to come back on to DM someone. Quickly checked the mentions.
“This app has contributed to making the last couple of years of my life absolute hell.
“When I was in my mid twenties, before there was even the term ‘troll’, I had a TV show. It wasn’t good but I was young and inexperienced.
“Nonetheless, that should have been an exciting time in my life. But instead I remember it for someone tweeting me ‘What is @seannwalsh and how do we make it die?’
“I must hear that echo in my mind every few weeks. I hate this place. It is poisonous.”
Walsh also addressed the people who had “abused” him on the platform.
He continued: “To everyone that has got in touch on here over the years to say you enjoyed one of my gigs or shows, thank you so much, I’m sorry I didn’t get back to all of you.
“Now. To everyone who has abused me on here, even the ones that didn’t @ me, from the bottom of my heart and all the energy I can will, f*** you. Really f*** you.
“I won’t miss this place. What even is it? In all my life, I don’t think I’ve actually heard anyone talk about the things people talk about on here in real life. Chill out and have a biscuit.”
Since the kissing scandal, Jones and her husband Neil have split.
However, the couple said the incident was not the cause and that their marriage had become more of a friendship than a romance.
Walsh has also addressed the incident during recent live shows.
