Open the image you want to crop in Illustrator. You can drag and drop the image file onto the Illustrator workspace or open it using the File > Open menu.
Select the image using the Selection Tool in the left tool tray. It looks like a black cursor with a white outline.
Using the Selection Tool, click on the image you want to crop. When it's highlighted, a box will appear around the edge.
To crop the image, use the Crop Tool. Go to Object > Crop Image. With the crop tool, you can adjust the image by dragging and dropping the edges.
When you've finished making adjustments, save the image or continue working with your Illustrator project.