final public function delete($capability) {

        if ( array_key_exists($capability, $this->rpc_capabilities) ) {

            unset($this->rpc_capabilities[$capability]);

            $this->logger->debug("Deleted capability $capability");

            return true;

        } else {

            $this->logger->warning("Cannot delete capability $capability: entry not found");

            return false;

        }

    }