Re: How can I reset the Sims 4? I want to go back the very beginning

You can click the + sign (top right corner) in the main menu to start a new game. That will take you to Create-A-Sim.

 EDIT: Click the sign next to the + sign to find your saved games. 🙂

If you want to play premades, you will need to create a sim (randomly generate one if you want too), randomize the name, and pick his/her traits.

Once in the world map, you pick a lot where the sim lives.

After that, go into Manage Worlds, you can delete your CAS sim and pick a premade.