It is nice to give credit where credit is due, but in some cases it just takes up space and just needs to go. In our case we wanted to remove the Submitted by and Date\Time from our polls. The submitter would be the same person every time, so no need to give credit. In fact this may be good practice for all site owner\editor generated content to remove this extra query and reduce the page size\load times.
For each content type where the Submitted by is not needed, go to "structure", then to "content types."