That sounds pretty odd! When you restart your game, you should automatically be back on your main account. The Wurst Client doesn't have any features that would keep you stuck on an alternate account.
Have you checked which account you're logged in with in your Minecraft launcher? That's the only place that controls which account you're signed into when you start the game.
Hope this helps! If you're still having trouble, please provide more details such as the name of the launcher you are using.