In Adobe Illustrator, you have several tools to help you crop images. The first one lets you select a rectangular area and delete the rest of the content. First, select the image and open the Object menu. There, click on Crop Image.

Crop the imageCrop the image

Adjust the area you want to crop.

Select the crop areaSelect the crop area

Click Apply to set the changes.

Apply the cropApply the crop

In addition to this method, you can create a custom selection with any shape using the stroke tool.

Selection toolSelection tool

Similarly, you can use the shape creation tool to create round or rectangular paths.

Shape builder toolShape builder tool

Create the path over the image to crop a specific portion.

Create an image traceCreate an image trace

When you are done, make sure that the path is above the image. Do this by right-clicking, and from the menu, selecting Arrange, and then, Bring to Front.

Bring the trace to the foregroundBring the trace to the foreground

Now, select the image and the path with the selection tool. Next, open the Object menu, Clipping Mask, and finally, click on Make.

Cut out the traceCut out the trace

Adobe Illustrator will isolate the selection from the rest of the image so you can work with it.

Result of the croppingResult of the cropping

Finally, to split an object into a grid, select it and open the Path option from the Object menu. There, click on Split Into Grid.

Crop the image on the gridCrop the image on the grid

Choose the number of columns and files and click on Ok.

Confirm the grid croppingConfirm the grid cropping

A grid will be drawn over your image, letting you divide it into several portions of the same size. Remember that, when you finish cropping your image, you must save the changes. You can do it as a project, in Adobe Illustrator's own format, or exporting the file as an image, using the extension that suits you best. This last option is available in the File menu, in the Export section.