Well, the easier way would have been way back when I first released this version and I told you (personally) to upgrade right away so you wouldn't run into this problem ;)

Now you have two choices:

1. Do it manually
2. Write a script to do it and share it with everyone on here :)

If you use FlashFXP you can search for certain files on a server and delete them.

Sod using a script.

run that from the top level dir in your photo directory.