In cities all over the world, the taxi industry has been turned upside down by Uber, the US rideshare company. The app's global expansion, often deliberately taking on complacent taxi firms and city halls, was led by Travis Kalanick. But his aggresive approach meant that by 2019, he had sold all the shares in the company he founded. Hear how he built Uber, what was he like to work for and how he was forced out.