The NPC who hands out the guildeve says you can return them after we finish, but I don't see the option. Can anyone tell me where or how to do this?
You can't hand in a regional leve in the same leve period you got it in. You have to wait for the leve refresh, which happens every 36 hours. If you'll look at the top of this page, you'll see a countdown timer for the next level refresh.