Open your Google Slides presentation and select the image you want to crop.

Click on the image, then select the "Crop" tool in the toolbar.

Click the dropdown arrow next to the crop icon and choose "Shape".

Select the circle shape from the available options.

Adjust the image inside the circle by resizing or repositioning it.

Click anywhere outside the image to apply the circular crop.

Resize or move the image as needed to fit your slide layout.