- Click on the "Play" button in the main menu;
- Choose a save slot that you'd like to use; choose "New Game";
- On the "New Game" menu, you'll find a check box for "RofG"
- Un-check the "RofG" box to disable the Reign of Giants content and start the game.
Doing the steps above will disable all of the Reign of Giants expansion content (including Webber and Wigfrid) and allow you to play the original, Don't Starve game.
*Please note that you will have to start a new game on a new save slot or overwrite an existing game in order to play the core Don't Starve experience.