It is possible to delete single messages and/or entire list archive files from the list archives via the web interface, if the list is configured to have web archives.

The archive index page for a given list looks something like this:

If you are a server administrator or an owner of the list, then a Recycling Bin icon () is displayed next to each message. Clicking on this icon allows you to delete the entire message from the archives.

NOTE:  Before the message is deleted, a confirmation page is displayed, giving you a chance to review or cancel your selection. Once deleted, the message is permanently erased and cannot be recovered.

There is also a Delete All option at the bottom right of the message index, which allows you to completely delete the current (open) notebook and all of the messages it contains.  

NOTE: Before the notebook is deleted, a confirmation page is displayed, giving you a chance to review or cancel your selection. Once deleted, the current message archive file is permanently erased and cannot be recovered.