For example, unban the IP xxx.xxx.xxx.xxx that has been banned from sshd:
fail2ban-client set sshd unbanip xxx.xxx.xxx.xxx
You can list the banned IP (basically firewall rules) with:
iptables -L
-> Look for the chain names, for example “Chain f2b-sshd” is holding list of banned IPs from sshd. (Chain f2b-postfix-sasl, Chain f2b-dovecot, Chain f2b-pure-ftpd…)