Have all the files got a common extension (eg .html). If they have, and they reside on the same filesystem, you could use find as follows, from the top level directory above your log directories:
find . -name '*.html' -mtime +31 -print |pg
This will list the files. If you're really sure you want to delete them, replace the -print command with -exec rm {} \; and take out the |pg at the end. Be careful with rm, however, it's a very dangerous command in this and any other context. You could add an -i option to the rm so that you are prompted for each file to be deleted, but this may not be practical if there are hundreds.
If this does not suit your requirements (eg because the files aren't on the same filesystem), you could write a script to cd to the appropriate directories and do individual finds and deletes on them as above. Hope this makes sense - post again if you require further info. Cheers.