A bulk write off can be done via the Archive From CSV, this will only work if you have the setting in Accounts Administration on Matter Archive to write off WIP.
Please follow the below steps to archive by CSV:
From the Main Menu select Archive From CSV.
On the CSV you will need the columns in the below order to be able to import.
Matter
Date
Location 1
Location 2
Location 3
Description
Then follow the next steps:
Save the CSV to your desktop to be able to import.
Select the CSV by clicking on the Magnifying glass.
Pick your options required when archiving.
Select ARCHIVE.
A message will appear to tell you that the archive has been done.