[libvirt] how to delete storage-pool entirely

it seems that if pools has the same path even with different uuid ,they will be recognize as one pool. if i have defined a pool with a special path, next time to define a new one(same path , different uuid) will fail. then i delete(rm -f ) pool.xml file, define the pool again , it fail too. so if there is cache for all pools been defined until next start libvirtd? my questions: 1. how to delete a pool entilely , include pool-xml file and possible cache (not to restart libvirtd).? 2.throught calling libvirt API , how to find the pool with a special path,no need to define it again? thanks