@Hao Ma , there is such a setting in compiler flags:  - e. But usually it is a very dangerous idea not to store global storage within the persistent class. As the storage is being generated, if not presented in a code on a target machine, it can become completely different from the data associated with the class that already exists, and this can lead to unpredictable data losses and failures. 

So usually, it is not recommended practice to delete the storage information from the class other than you are sure that there is no data in the system or it is deleted in advance.