How to Kick All Players Using a Script?

Player has a method called Kick for kicking the player off the server, with an optional parameter for what message to show them. The NumberValue class, as well as some of the other ones such as StringValue, also have an event that fires for whenever the value is changed called Changed. Given this information, all that needs to be done is check if the value is less than or equal to 0 in a function connected to the Changed event, and then call the kick method on every player if it is.

local Players = game:GetService("Players")
game.Workspace.Wall.NumberValue.Changed:Connect(function(value)
    if value <= 0 then
        local players = Players:GetPlayers()
        for i, player in ipairs(players) do
            player:Kick("get out")
        end
    end
end)

Use for do loops

for i, v in pairs(game.Players:GetChildren()) do
    if v then
        v:Kick("Message here")
    end
end

Edit the script to your needs

Links:

https://developer.roblox.com/en-us/articles/For-Loops

https://www.youtube.com/watch?v=UsrtGk5E71w

Put this script anywhere on the server:

game.Workspace.Wall.Health.Changed:connect(function(value)
    if value <= 0 then
        for i,Player in pairs(game.Players:GetChildren()) do
            Player:Kick("Lol bye")
        end
    end
end)