You can use a bash script to do it:
#!/bin/bash cd $(dirname $0) # Don't screw us up with spaces! IFS=$'\n' DIRS=$(find . -type d -name "rules") for i in $DIRS; do rm $i/*.pdf done This iterates through the directories you find in your find command and removes the pdf's under each directory.
EDIT: This would fail upon encountering a directory with whitespace in its name. To fix that, add the line IFS=$'\n' to the beginning of the file, as shown above.
Of course, this is assuming you don't have newlines in any of your filenames. If you do, the solution will become a lot more complicated.