Why was icc name changed from imperial cricket conference to the international cricket conference?

The name was changed because of decolonisation. This was a process by which the British influence in many areas, one of them sports, declined. Cricket was no longer the monopoly of the imperial powers. Cricket was becoming international. In time, it came to be accepted that the laws of cricket could not continue to be framed for British or Australian conditions of play and they became part of the technique of all bowlers, everywhere in the world.