First, we must find all infested files using following command.
root@hr# cd /home/username/public_html/
root@hr#grep -lr --include=*.php "eval(base64_decode" *
How to Remove the code ?
grep -lr --include=*.php "eval(base64_decode" /home/username/public_html/ | xargs sed -i.bak 's/<?php eval(base64_decode[^;]*;/<?php\n/g'
Please try it.