The St. Kitts and Nevis team said it "regrettably announced" that Collins, who it described as a "national hero," was leaving the Olympics.
Collins was kept out of his scheduled start in the 100 heats on Saturday. He was also entered in the 200 and 4x100 relay.
"Mr. Collins departure is down to his repeated absences from training sessions and also for refusing to respond to repeated phone calls and emails by team manager and coaches," the St. Kitts and Nevis Olympic Committee said in a statement. "Furthermore, Mr. Collins did not make an appearance for registration for his events at the Olympic Village (on Friday) as requested."
Collins told BBC Radio that his accreditation was canceled — effectively expelling him from the London Games.
"I am not walking away. I was pushed out," the 2003 world champion said. "I have to go home ... maybe this Olympic medal ain't for me."
Collins was hoping to compete in his fifth straight Olympics and carried the St. Kitts and Nevis flag at the opening ceremony.
His absences from official accommodation and team meetings included visits to see his wife.
"They're asking me to abandon my wife for the team. It's not going to happen," Collins told the BBC.
Earlier Saturday, Collins had posted on his Twitter account that "Even men in prison get their wives to visit."
Before his expulsion was confirmed, Collins suggested that the 2011 Pan American Games, where he won silver in the 100, would be his final appearance for the Caribbean state.
"For those who saw me run in Mexico. That's the last time I represent my country," he wrote.
Collins was an international star who would be "greatly missed by the whole nation," the team said.
"Mr. Collins absence from London 2012 is a huge disappointment for the team and for the country, who will not witness their national hero perform at this largest global sports event," St. Kitts team manager Lester Hanley said in a statement. "We wish him well."
Collins is the second of an original seven-athlete Olympic team from St. Kitts and Nevis to be disciplined. Sprinter Tameka Williams, the only woman on the team, was sent home last weekend for a potential drug violation despite not testing positive for a banned drug.
The St. Kitts and Nevis Olympic Committee said Williams had acknowledged using a substance which was "clearly outside the medical code."
