To remove a valid IP address from the iptables, log in via SSH and enter the following commands:
iptables-save > tmp_file
nano tmp_file
Remove / delete the line containing the valid IP address
iptables-restore < tmp_file & iptables-save
To block an IP (example 111.222.333.444), please use the following command:
iptables -A INPUT -s 111.222.333.444 -j DROP & iptables-save