RAW files are never altered by your manipulations within the RAW module, rather the application creates a set of instructions that travel with the RAW file, applying your previous edits to the image when you open it in a "new" RAW session. The image you see on screen within the RAW module are representations of what your file will look like when, once you are happy with your RAW adjustments, you save the file to another format. Once you have saved the file to that different file format, then you can actually move/remove/distort the actual pixels in your image, which simply cannot be done to a RAW file. BTW, you don't have to save to a new file format during any particular RAW editing session, you can simply exit RAW and the app will keep track of what you have done up to the point that you decided to exit. The next time you open that file in ACR, your progress is restored to the state that you last worked on it. Think of your RAW file as your "source" for the image, you cannot change the source itself, but you can alter the way the image looks, and when you are happy with those adjustments, you send it out of RAW and save it to your file format(s) of choice. Once your file is exported to your preferred file format, then you can perform "destructive" pixel manipulations, like content aware cropping.
