[HELP] How to make the loader hide after loaded the main UI?

The title says it all.

So this is my code for the loader:

string CurrentVersion = "1.2";
            if (client.DownloadString("mylink") == "true")
            {
                KeySystem key = new KeySystem();
                key.Show();
                this.Hide();
            }
            else
            {
                Executor exec = new Executor();
                exec.Show();
                this.Hide();
            }

But all it does is check properly but when it shows the executor, the loader stays there. It's really annoying, anyone got any idea on how to fix that and make it not visible? It also shows like in another tab of the application, for example:

https://cdn.discordapp.com/attachments/915277519207432314/948607087758418050/unknown.png