The definition of veganism is, according to The Vegan Society:
'Someone who tries to avoid - as far as is possible and practical - all forms of exploitation of animals for food, clothing or any other purpose. This is for the benefit of people, animals and the environment. Vegans eat a plant-based diet free from all animal products, such as meat, animal milks, eggs, honey and gelatine. They also avoid animal products like leather, wool and silk for clothing or other purposes'.
It is definately un-vegan to wear animal skins/leather!
I admit I have a few wool items from before I went vegan, such as a pair of trousers and a couple of expensive sweaters. I have not thrown them away as they were presents, but would feel very uncomfortable wearing any form of animal product whilst being vegan.