Help for UNBAN:

The UNBAN command allows you to unban a user or hostmask
from a channel. If no nickname or hostmask is specified,
you are unbanned.

Syntax: UNBAN <#channel> [nickname|hostmask]

Examples:
    /msg &nick& UNBAN #chat pfish
    /msg &nick& UNBAN #chat *!*@*.ucdavis.edu
