Have you gone through the ticket generation process and decided you want to select a different wager type? No worries, you don't need to hit the undo button. All you need to do is start a new wager.
Use The "Start New Wager" Button
Once you've generated any kind of ticket the Start New Wager button appears under the stats table:
Click the Start New Wager button and you will be able to start the ticket generation process over from the beginning with any wager type you desire.