VERIFIED SOLUTION i
1. Delete Temporary File Storage location that keeps Ad-hoc attachments, created for a company.
From the Admin Website->Configuration->Temp and delete the storage location.
2. Delete a particular attachment within a temporary storage location,
From the Admin server, default location is OFMA\temp folder, find an attachment by its name and delete it.
3. Edit PI-OFMA-DAFAULT role
From the Admin website-Organisation-Roles, remove the tick on Temp location box, users with this role assigned will not be able to use that temp location.
UPDATED: June 26, 2017