How to unban a player in CS:S
Type removeid STEAM_0:1:12345678 in the server console to lift that Steam ID ban, then writeid to save the change.
removeid
Removes a Steam ID ban.
removeid <steamid> Examples
removeid STEAM_0:1:12345678 Unban a player.
Arguments
steamidRequired- Steam ID to unban.
What it does
Run writeid afterwards so the change is saved.
The game's own description: Remove a user ID from the ban list.
Run it on your server
On a SLASHPLAY server, type it in the Console tab of the server page; the reply shows right under it. A value set there lasts until the server restarts. To keep it, add the line to cstrike/cfg/server.cfg. New to this? Start a CS:S server first.
Your own
CS:S server.
From $0.03 an hour, only while it runs. New accounts get 6 free tokens.