To make images appear as “part” of a slide, you can make them transparent. This guide will show you how to make an image background transparent in Google Slides easily.
Make an image transparent using Format Options
- Navigate to the image you want to make transparent.
Select the image. - Right-click the image. From the list of options, choose Format options.
Right-click and select Format options. Alternatively, you can select Format options from the top toolbar.
Click Format options from the toolbar.
- The Format options panel will show up on the right side of your screen.
Expand the Adjustments menu and drag the Transparency slider to your desired percentage. By default, it will be set to zero or on the leftmost side. Dragging it to the rightmost side will make the image completely transparent.
Expand the Adjustment menu and adjust the slider. 
The image has been made transparent.