If it slowed down over several years, it would still be a disaster. Without centrifugal force, the oceans would move towards the poles, dropping ocean depth by 8km around the equator. If the Earth rotated at a speed of 299 792 kilometers per second that would be 652 000 times faster than today dimensions of the planet would change once a sphere the Earth would contract into a thin disc like shape and so would you along with every other object.