Javascript created to write file with variable, but not saving data into csv when runing from load agents.

Question 1:

Created a javascript to write variables into csv file, working fine when run from localhost agent,

But when run from load agent, the csv file is not getting updated.

Question 2:
how to write a javascript that can delete a row from csv after using the row during the run time or end of the run delete all rows which are used. So need javascript that can delete number of rows from csv.

Please provide your inputs.

Thanks in advance!!!