Originally Posted by Swish

find / -type f -name *.html -exec grep -l "search_text" {} \; | perl -pi -e 's/search_text//g'

You'll have to regex escape the search_text but that's how I would do it.

If you want to make a backup of the files before changing them make it 'perl -pi.bak -e' for that part instead which will copy the chaged file and add '.bak' to the name