What should I do with my leather or fur shoes if I am vegan?

Give them to homeless folks. If more homeless folks are wearing "high fashion" less rich people will buy it and they will stop making it eventually. Rich folks don't want to wear fur when they see a bunch of poor folks wearing it en masse (in such places like NYC or Paris and other high fashion cities). Don't just donate them to a thrift store and don't sell them but give them to someone living on the streets it will help them and also hurt the industry.