You would not be able to remove the file locking from the UBB without seriously overhauling the inner workings, in addition to causing your UBB to go totally nuts with corruption issues, especially on a busy board.
Your host has gone insane, and frankly, you should find somewhere else, IMO.
If you don't want to go somewhere else, you could always convert to UBB.threads which is PHP/MySQL based.
