If you want to start your game completely over in Forza Horizon 5 on the Xbox One, Xbox One S, Xbox One X, Xbox Series S or Xbox Series X, then you can check out this guide at Game Idealist.
How to start a new game file in Forza Horizon 5 using a different account
You can start a completely new game in Forza Horizon 5 by signing into a different account. In order to do so, you need to take the following steps:
1. While playing the game, bring up the pause menu.
2. In the first page of the pause menu, select Settings.
3. Inside the Settings menu, press the X button on your Xbox One or Xbox Series controller to select Change profile.
4. In the Change Profile notification, select Yes.
5. In the “Who are you?” menu, you can sign into another account or add a guest account.
6. In the Profile Changed screen, press the A button to restart Forza Horizon 5 with a new game file.
How to start a new game file in Forza Horizon 5 using the same account
To start a new game in Forza Horizon by using the same account, you first need to delete your old save file. Keep in mind that this will completely delete your progress. If you are still interested in doing this, then you need to take the following steps:
1. If you haven’t already, close Forza Horizon 5
2. Press the Xbox button on your controller to open the Guide menu.
3. In the Guide menu, select “My games & app.”
4. Next, select “See all.”
5. In the next screen, select “Games” from the left column.
6. Highlight Forza Horizon 5 on the right side of the same screen and then press the menu button on your controller.
7. In the pop-up menu select “Manage game and add-ons.”
8. In the “Manage – Forza Horizon 5” menu, select “Saved data.”
9. In the “Forza Horizon 5- Saved data” menu, select your profile.
10. In the notification, you can either select “Delete from Console” or “Delete from Everywhere.”