Here is work around for this. Write a bat file and keep under Alteryx workflow event after run. Below is screen shot for better understanding. Hope it works until Alteryx provide in-built option to ignore bak file as outcome of output file tool.
Yes would love to turn off or direct to another folder as work folder is linked onto a OneDrive 4 Business account (ensures work is backed up by group policy) which doesn't like .bak files
I'm constantly manually deleting my .bak files because I don't need the clutter. Please give us an option to turn off their creation, or at least designate a separate folder for all .bak files.