code: private void revokeClassicDbSecurityGroup(String groupName, String sourceCidr) throws CloudException, InternalException {
          Map<String,String> parameters = getProvider().getStandardRdsParameters(getProvider().getContext(), REVOKE_DB_SECURITY_GROUP_INGRESS);
  
          parameters.put("CIDRIP", sourceCidr);
          parameters.put("DBSecurityGroupName", groupName);
          EC2Method method = new EC2Method(SERVICE_ID, getProvider(), parameters);
          method.invoke();
      }
docs: Use this to revoke access of security groups in EC2-Classic
  @param groupName
  @param sourceCidr
  @throws CloudException
  @throws InternalException