STEP # 1

From the Canvas, click the Pre-Quiz Page to edit it. Make sure you click the one on the Canvas page and not the one under the Components menu.

Click Builder - this action will automatically open the Builder menu with three sections:

STEP # 2

Once the Pre-Quiz Page is open, click the Container where the Background image is located, then click on Properties, and scroll down to find the Images & Backgrounds section. Another route is by clicking the arrow next to each section to collapse them until you get to the Background Image section.

STEP # 3

A small preview of the background image will be displayed in the Images & Backgrounds section. Now click on the Trash can icon to delete the current image or double click small preview

STEP # 4