If you are the owner of a Colorado building or property that allows public access, and do not wish open carry firearms to be allowed on the premises, you must comply to Colorado's open carry sign laws pursuant to C.R.S. 29-11.7-104.
A local government may enact an ordinance, regulation, or other law that prohibits the open carrying of a firearm in a building or specific area within the local government's jurisdiction. If a local government enacts an ordinance, regulation, or other law that prohibits the open carrying of a firearm in a building or specific area, the local government shall post signs at the public entrances to the building or specific area informing persons that the open carrying of firearms is prohibited in the building or specific area.