I don't remember ever hearing of a formal disbanding, I think, technically, it's still around, just by another name. After the British Crown took control of India as a part of its formal empire, the East India Company just moved to the background.
E.I.C. was disbanded in 1857 after the Indian revolt of 1857 and the reason was the discontent among the people because of the unjust company's rule and to prevent the occurrence of such a revolt in the future. Queen Victoria became Empress of India.