I use fail2ban to stop annoying things like ssh bruteforcers, etc.
Sometimes I accidentally manage to get my own address added, or need to unblock a specifc address. Here's how:
user> sudo fail2ban-client status sshd
Status for the jail: sshd
|- Filter
| |- Currently failed: 0
| |- Total failed: 3
| `- File list: /var/log/auth.log
`- Actions
|- Currently banned: 1
|- Total banned: 1
`- Banned IP list: 192.0.2.1
And then to remove the IP:
user> sudo fail2ban-client set sshd unbanip 76.104.43.89