you can set its status as enemy/neutral with other factions but i dont think you can with non faction players
/faction_mod_relation 1001 -3 enemy
the 3 arguments are Faction ID, Faction ID & status (enemy , neutral, ally)
/faction_mod_relation 1001 -3 enemy
the 3 arguments are Faction ID, Faction ID & status (enemy , neutral, ally)