you use a usersfile table to create the many to many relation of users to files right?
If so, you would need to pass the UserID and File ID for the Delete
you would need to use the DW Recordset behavior to create the delete statement to delete the record from the usersfiles table.
The User ID should be stored in a session and the file ID would be passed through a form variable. The recordset would look similar to:
DELETE FROM userfiles WHERE userfileUserID = paramUserID AND userfileFileID = paramFileID
then in the variables section create the 2 variables as:
Name: paramUserID
type: integer
Default Value: -1
Runtime value: $_SESSION['UserID']
Name: paramFileID
type: integer
Default Value: -1
Runtime value: $_POST['FileID']