code: public Observable<Void> deleteAtResourceGroupLevelAsync(String resourceGroupName, String lockName) {
          return deleteAtResourceGroupLevelWithServiceResponseAsync(resourceGroupName, lockName).map(new Func1<ServiceResponse<Void>, Void>() {
              @Override
              public Void call(ServiceResponse<Void> response) {
                  return response.body();
              }
          });
      }
docs: Deletes a management lock at the resource group level.
  To delete management locks, you must have access to Microsoft.Authorization/* or Microsoft.Authorization/locks/* actions. Of the built-in roles, only Owner and User Access Administrator are granted those actions.
  
  @param resourceGroupName The name of the resource group containing the lock.
  @param lockName The name of lock to delete.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the {@link ServiceResponse} object if successful.