/SLASHPLAY
How to undo in GMod
Type gmod_undo in your game console to remove the last thing you spawned or built. The Z key does the same.
gmod_undo
Undoes the last thing you spawned or built in Sandbox.
gmod_undo Examples
gmod_undo Remove your last spawn.
What it does
Each use removes your most recent undo entry, such as a prop, weld or tool action. The undo key, Z by default, does the same.
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.