It is the most drastic way but it is also the most effective one. If you are using WordPress then export all the content to your local disk and make sure you have saved other things but do save them manually and then erase all the server and do a clean install and then import the posts et cetera.
You can also use some paid malware removal services. Some are quite affordable and there are plenty of them. You need to find them by yourself because unfortunately, the one that I have used once is not in the business anymore.
Also take a look at this topic and if you see similarities then you might consider moving out to another hosting.
webhostingtalk.com/showthread.php?t=1024036
webhostingtalk.com/showthread.php?t=1638031
webhostingtalk.com/showthread.php?t=1671295
webhostingtalk.com/showthread.php?t=1443199
After reading these, I would not host my sites with them to be honest with you.