We would love to include Audya - We need to get a unit in-house first. Assuming that we move forward with the whole webinar concept (which is looking better by the day) we will certainly try to find a way to offer that at some point in the future. Now, can't say this will work in your case but I just tried it on SD90 so I'm expecting it should be similar steps on Audya.
1 - Touch Media.
2 - Touch the icon for the primary storage device in your unit.
3 - Scroll to the Registration Folder.
3 - Select the Bank the registrations are in that you want to delete.
4 - Locate the registration(s), select and touch the delete button.

Let me know if that worked?