We're out for the holiday, so I can't confirm until next week, but I believe the way it works is this:

If you had a name, and reserved that name for an upcoming game, no one else could take that name in that game before you.

Once you have used that name, however, I don't think it is reserved anymore. Therefore if you delete your character someone else could theoretically take that name. It had been reserved, then used, and then discarded. I don't think there is a permanent reservation.

But again, not sure. Will confirm next week.

Happy New Years!

- g