code: public OperationFuture<FirewallPolicy> delete(FirewallPolicy firewallPolicy) {
          FirewallPolicyMetadata metadata = findByRef(firewallPolicy);
  
          firewallPolicyClient.delete(
              metadata.getDataCenterId(),
              metadata.getId()
          );
  
          return new OperationFuture<>(
              firewallPolicy,
              new NoWaitingJobFuture()
          );
      }
docs: Delete firewall policy
  
  @param firewallPolicy firewall policy
  @return OperationFuture wrapper for firewall policy