From Minecraft Wiki
Removes entries from the banlist.
- Specifies the name to remove from the banlist.
- Specifies the IP address to remove from the banlist. Must be a valid IP address.
- Fails if the arguments are not specified correctly.
- On success, if the name or the IP address is on the banlist, it is removed, allowing anyone to connect to the server by that name or from that IP address.