How to kick a player by SteamID in GMod
Type kickid STEAM_0:1:12345678 AFK in the server console to kick that player with the reason AFK. status shows SteamIDs and user IDs.
kickid
Kicks a player by user ID or SteamID, with an optional reason shown to them.
kickid <userid|steamid> [reason] Examples
kickid 5 Spamming props Kick user ID 5 with a reason.
kickid STEAM_0:1:12345678 AFK Kick by SteamID.
Arguments
userid|steamidRequired- User ID from status, or the player's SteamID.
reasonOptional- Message shown to the player.
What it does
Get the user ID or SteamID from status. The reason is displayed on the player's disconnect screen.
The game's own description: Kick a player by userid or uniqueid, with a message.
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 garrysmod/cfg/server.cfg. New to this? Start a GMod server first.
Your own
GMod server.
From $0.03 an hour, only while it runs. New accounts get 6 free tokens.