So you have a zombie process, in my case varnish and I couldn’t kill it with kill -9 PID or killall -9 varnishd..
Use: ps fauxwww – It will show you a branch of processes and you want to kill it’s parent process, in my case it was bash. Don’t do killall bash, that would just be stupid. Do kill -9 PID_of_bash_parent..
That is all, now you too can kill zombies.