How can I remove a StarterGUI for a certain team?

You can't remove StarterGui, as that's the instance that replicates the GUIs to the player instances, thus removing it is irrelevant to your situation.

What you can do, though, is removing the ScreenGUI object itself.

-- If this script is a system script that manages every player in the game
for i, v in pairs (game.Players:GetPlayers()) do -- Get the players
    if v.TeamColor == "Bright blue" and v:WaitForChild("PlayerGui"):FindFirstChild("YourGuiHere") then
-- If the player is in Bright blue team and has the GUI itself 
        v.PlayerGui.YourGuiHere:Destroy()
    end
end

If you meant to remove all of the GUIs of the players of a certain team...

for i, v in pairs (game.Players:GetPlayers()) do
    if v.TeamColor == "Bright blue" then
-- If the player is in the Bright blue team
        for i, obj in pairs (v:WaitForChild("PlayerGui"):GetChildren()) do
-- Gets everything in the PlayerGui
            if obj:IsA("ScreenGui") then -- Just in case
                obj:Destroy()
            end
        end
    end
end
-- Simple iteration of the players and the PlayerGuis