$ find -name *.pdf | xargs rm -f
$ rm -f $(find -name *.pdf)
$ for i in $(find -name *.pdf); do rm -f $i; done
You may want to try and cat the files instead of rm'ing them, just in case--spaces and other weird characters in the filenames may not be handled gracefully by my examples (they should be irrelevant in alienDog's code); try setting IFS to '\n'.
Try playing around with the various mechanisms and programs I mentioned; rtm and backup vital data before doing anything stupid