How update a csv file

i have a list of store and every week day update.
i use google sheet for read them but in iran we have problem with conection to goole sheet.
so i change my app form google sheet to csv file.and i need to deleting all data in my csv file and agein i record new item to csv file.
how can i update my csv file?
thanks a lot

You have a choice, either set your exiting file to empty or delete it altogether and start again