@Override
  public void unregisterFunction(String functionId) {
    if (functionId == null) {
      throw new FunctionException(String.format("%s passed is null",
          "functionId instance "));
    }
    idToFunctionMap.remove(functionId);
  }
use when the optimization to execute onMember locally is not desired.
geode-core/src/main/java/org/apache/geode/internal/cache/execute/InternalFunctionExecutionServiceImpl.java