Here are the steps to crop an image in Preview on your Mac:
1. Open the image you want to crop in Preview.
2. Use your mouse or trackpad to select the portion of the image that you want to keep. While selecting, you will see the crop dimensions.
3. Once you have selected the area you want to keep, click on the "Crop" button in the toolbar or use the Touch Bar.
4. To undo the crop immediately, choose Edit > Undo Crop.
That's it! You have successfully cropped your image in Preview on your Mac. Let me know if you have any other questions.
[Here](https://support.apple.com/guide/preview/crop-or-rotate-a-pdf-prvw11567/mac) is a link to Apple's official guide on how to crop or rotate a PDF in Preview on Mac if you are interested.
