The only other possible way to delete them is if your host will recover
a backup for you; however, this would mean possibly losing current
posts. Here are a few suggestions I have for keeping "backups" of your
forum.
(1) One of the advantages of using Access is that you can download the
.mdb file very easily for backup. To automate this, use a combination
of programs such as
WebDrive and
SecondCopy.
WebDrive will map a network drive to your FTP and SecondCopy makes
automatic backups a breeze. Both apps are not very expensive at all. If
you have a machine on broadband that is always on, then you are good to
go.
Note: If you forum is busy, you will need to weigh the performance benefits of SQL Server over database ease with Access.
(2) Subscribe to each forum using an email address and make sure that
you have your forum set to send the post with the email. Gmail works
very well with this as it threads the emails similar to the forum
threading. Of course, depending on your hosting, you may or may not be
able to send this much email out. (If you need a Gmail account, I have
50 available)
(3) If using Access, the "compact and repair" function in the Admin
actually makes a temporary copy of the database during the process. You
could mod this to leave that temporary copy on the server and use
occasionally use the script as a "poor man's" backup. Remember to lock
your forum before using it.
As a side note, I don't usually allow people to delete their posts,
only edit them. Deletion is reserved for mods or admins only and by
request from normal users.