You can only kill one elk. Either a bull during modern or your special permit for a cow. IF you drew a second elk tag obviously thats a different story.
And you can turn in a tag to get your points back but you would have had to do it a long time ago, not long after you found out you got drawn. I know this because I have friends who have drawn a tag that they didn't mean to put in for and didn't want to waste points, or had other commitments (like having a baby) so couldn't hunt.