Question regarding Admin rights in hosted server

Launching a locally run listen server (ie using “Create Multiplayer” instead of a dedicated server client), how do I add other people to the admin or allow the use of all items? Last night a friend and I attempted to do some script testing on a weapon but it’s got the badge icon on it (I’m new to Garry’s Mod but I assume it means Admin only as I can use it) so he wasn’t able to use any of them.

tl;dr version: how do I add others to admin list on listen servers