How could a non-cooperation movement become …

Gandhi declared that British rule was established in India with the cooperation of Indians, and had survived only because of this cooperation. If Indians refused to cooperate, British rule in India would have collapsed.
(i) Non-cooperation movement was launched by Gandhi in 1920 and it was unfolded in stages. It began with the surrender of titles that the government awarded, and a boycott of civil services, army, police, courts, schools and foreign goods.
(ii) Various social groups participated in this movement, each with its own specific aspiration. The non-cooperation movement started with the middle class participation in the cities.
(iii) Thousands of students left government-controlled schools and colleges; headmasters and teachers resigned; and lawyers gave up their legal practices.
(iv) Foreign goods were boycotted, liquor shops picketed, and foreign clothes burnt in huge bonfires. In many places, merchants and traders refused to trade in foreign goods or finance foreign trade.