On Monday, the Delhi High Court convicted Kumar for his role in the 1984 anti-Sikh riots and sentenced him to imprisonment for life.
A day after Congress leader Sajjan Kumar was convicted and sentenced to life term for "remainder of his natural life" in the 1984 anti-Sikh riots case by the Delhi High Court, Kumar on Tuesday submitted his resignation from the primary membership of the party.
He has also written to party president Rahul Gandhi, sources in the party said.
"I tender my resignation with immediate effect from the primary membership of the Indian National Congress in the wake of the judgement of the hon'be high court of Delhi against me," he said in the letter to Gandhi.
The case relates to killing of five Sikhs in Raj Nagar part-I area in Palam Colony in South West Delhi on November 1-2, 1984 and burning down of a Gurudwara in Raj Nagar part II.
The high court directed 73-year-old Kumar and other five convicts to surrender by December 31, 2018 and not to leave the city of Delhi.
Six accused, including Sajjan Kumar, who was a Member of Parliament at that time, were sent for trial in 2010 and three years later, the lower court had convicted five of the accused but acquitted the Congress leader of all the charges.
PTI