How do i remove tags from an object?

What i want: at the end of a round the main script triggers a separate script to remove tags from spawners so enemies do not spawn in locations the player wont have access to.

what error im seeing: Unable to cast value to Object
Stack Begin - Studio Script 'ServerScriptService.DisableSpawns', Line 3 Stack End

Heres the code:

local CollectionService = game:GetService("CollectionService")
local OBJ = game.Workspace.Map.Normal:GetChildren("A1" , "A2" , "A3" , "A35" , "A4" , "A5")
for _, tag in ipairs(CollectionService:GetTags(OBJ)) do
    CollectionService:RemoveTag(OBJ, "spawner")
end
wait(3)
script.Disabled = true

I have multiple parts called "A1", "A2"... etc. and they're tagged "spawner" if a player buys a certain door.