I have a CD-RW disc that I want to erase. I'm sure this can be done as it is a RW disc. But when I go into disk utility to erase it, it confuses me like nothing else. And scares me a bit lol. I don't want to do anything to my system. Just erase the RW disc so I can use it again. But if you look at the picture below, I don't know which volume to select! Please give me instructions on how to erase my disc and not do anything to my system please. Thanks