Why I start process by debug then it goes to end event directly but not shows the interface of process start form

It didn't report any error so far

Hey buddy, we can support you better if you share more details. How is this process used? related action, scheduled, application action, subprocess? how its built- perhaps you can share a screenshot and process documentation(can be generated by appian) This a faar to generic as question

I already did a!writeToDataEntity to that button which i make at interface, but meanwhile i wish it can delete relevant data from another table simultaneously

okay you have a lot of questions at the same time.
1.) you cannot call for a start event with form if you use a process as suprocess or "start process linke or node.
You have to use start event, interface, then action.
2.) I would not reocomment writetodatastore smartservice and start process at the same button action (if its even possible in a clean way)
3.) use soft delete method: which means -> create a value at your cdt called "isDeleted" (type boolean) and your query rules ignores data marked as "isdeleted". So you can store data to different tables via writetomultipledatastore smartservice or node in your process. 

okay you have a lot of questions at the same time.
1.) you cannot call for a start event with form if you use a process as suprocess or "start process linke or node.
You have to use start event, interface, then action.
2.) I would not reocomment writetodatastore smartservice and start process at the same button action (if its even possible in a clean way)
3.) use soft delete method: which means -> create a value at your cdt called "isDeleted" (type boolean) and your query rules ignores data marked as "isdeleted". So you can store data to different tables via writetomultipledatastore smartservice or node in your process. 

I wish to do insert and delete at the same time which is my boss required, and I am not eligible to do any change in the database table,

By the way could you give me a a!startProcess sample, what should i fill in the processParameter, what processParameter about?

Hi,

In order to start a process by a!startProcess, you need to pass process model name and variables which are parameterised in your process model.

You can pass process parameters as key value pair, where the keys are process parameter names and the values are parmeters' values. If any required parameters are missing or if the dictionary contains any entries that do not match parameters of the selected process model, the process will not start.

Example:

a!startProcess(
      processModel: cons!UPLOAD_STUDENT_TRANSCRIPT,/*CONSTANT POINTING TO PROCESS MODEL TO BE STARTED*/
      processParameters: {
         /*PARAMETERISED VARIABLES IN PROCESS MODEL*/

         employeeId: 12345,
         deadline: today()+30
     }
)