Why can't :Destroy() destroy a model?

Hi everyone. I've been having an issue with the :Destroy() function which won't allow me to destroy any models.

I've been attempting to create a battle-royale style game and the main game script is supposed to remove the map after the game has finished by using the :Destroy() function, however once the game finishes the output throws out the error "Unable to :Destroy() Terrain". In an attempt to solve this, i've completely ungrouped and regroup the entire terrain model with no success, and i'm not quite sure as to what to do next. Any help is greatly appreciated.

CODE:

local s = script.Stat
local vals = game.ReplicatedStorage.vals
t = 0
while true do
    local plrs = game.Players:GetChildren()
    if #plrs >0 then
    t = 15
    repeat
        t = t-1
        s.Value = "Intermission... "..t
        wait(1)
    until t==0
    s.Value = "Game Starting!"
    wait(2)
    local mapselect = game.ReplicatedStorage.Games:GetChildren()
    local choose = math.random(1,#mapselect)
    curnum = 0
    for i =1,#mapselect do
        curnum = curnum +1
        if curnum == choose then
            mapselect[i]:Clone().Parent = workspace
            curmap = mapselect[i].Name
        end
    end
    wait(3)
    local plrs = game.Players:GetChildren()
    for i = 1,#plrs do
        local num = math.random(1,3)
        plrs[i].Character.Head.CFrame = CFrame.new(workspace.Teleports["Part"..num].Position)
        plrs[i].Character.Parent = workspace.Ingame
    end
    t=300
    repeat
        t = t-1
        s.Value = t.." seconds left!"
        wait(1)
        local ingame = workspace.Ingame:GetChildren()
    until t ==0 or vals.Winner.Value ~= "" or #ingame == 0
    if vals.Winner.Value ~= "" then
        s.Value = vals.Winner.Value.. " has won!"
        workspace[curmap]:Destroy()
        game.Players[vals.Winner.Value].leaderstats.Points.Value =game.Players[vals.Winner.Value].leaderstats.Points.Value +50
        game.Players[vals.Winner.Value].leaderstats.Wins.Value =game.Players[vals.Winner.Value].leaderstats.Wins.Value +1
        vals.Winner.Value = ""
    else
        s.Value = "No one has won!"
    end
    workspace[curmap]:Destroy()
    wait(3)
    local ingame = workspace.Ingame:GetChildren()
    for i =1,#ingame do
        local plr = game.Players:GetPlayerFromCharacter(ingame[i])
        plr:LoadCharacter()
    end
    else
        s.Value = "Two or more players are needed to play!"
        wait(1)
        end
end